MDD 'Wind tunnel' PS Fans - Recommended replacements?

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD G4 PowerMac?
Andy wrote on :

Hi there,

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD G4 PowerMac? I've finally had enough of the noise - even my housemate's PC over in the other corner of the room doesn't even make HALF as much racket as this thing.

In particular, I'm looking for specific brands/part numbers that worked well so I don't go through the hassle of replacing them for no benefit. Links to Aus suppliers would be greatly appreciated too.

Cheers, Andy.

Andy replied on :

Andy wrote:

Hi there,

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD Dual G4 PowerMac? I've finally had enough of the noise - even my housemate's PC over in the other corner of the room doesn't even make HALF as much racket as this thing.

Just to followup, I took a punt on purchasing a pair of these:

http://www.pccasegear.com/prod4273.htm

(And no, I wasn't particularly swayed by the blue LEDs, it seemed to have the best CFM/dBA specification however.)

I'll post results provided I don't kill the machine/myself in doing the replacement.

Cheers, Andy.

denis replied on :

On 2007-10-07 13:17:37 +1000, Andy nospam@redacted.invalid said:

Andy wrote:

Hi there,

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD Dual G4 PowerMac? I've finally had enough of the noise - even my housemate's PC over in the other corner of the room doesn't even make HALF as much racket as this thing.

Just to followup, I took a punt on purchasing a pair of these:

http://www.pccasegear.com/prod4273.htm

(And no, I wasn't particularly swayed by the blue LEDs, it seemed to have the best CFM/dBA specification however.)

I'll post results provided I don't kill the machine/myself in doing the replacement.

Cheers, Andy.

If you do kill yourself, can you get a buddy to post ;-)

Emma Grey replied on :

In article 47078914$0$3589$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

Hi there,

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD G4 PowerMac? I've finally had enough of the noise - even my housemate's PC over in the other corner of the room doesn't even make HALF as much racket as this thing.

In particular, I'm looking for specific brands/part numbers that worked well so I don't go through the hassle of replacing them for no benefit. Links to Aus suppliers would be greatly appreciated too.

Cheers, Andy.

Funnily enough, I actually LIKE the noise of my MDD G4. It's a sort of noise blanket and acts as an aid to concentration - by covering more salient noises. The theory is that the brain 'learns' the noise and thus doesn't attend to it. Sounds like you're hacking the hypothesis.

Oh well, it's postmodern world we inhabit?

MA

Andrew replied on :

I sold my G4 MDD to a company where it has been running OSX server perfectly for 2 years. It was one of the later ones but still really noisy by current standards. Now it has its own server room to whirr away in where it does not disturb anyone !

Cheers andrew

On 8/10/07 11:26 PM, in article 081020072326308391%gone@redacted.invalid, "Emma Grey" gone@redacted.invalid wrote:

In article 47078914$0$3589$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

Hi there,

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD G4 PowerMac? I've finally had enough of the noise - even my housemate's PC over in the other corner of the room doesn't even make HALF as much racket as this thing.

In particular, I'm looking for specific brands/part numbers that worked well so I don't go through the hassle of replacing them for no benefit. Links to Aus suppliers would be greatly appreciated too.

Cheers, Andy.

Funnily enough, I actually LIKE the noise of my MDD G4. It's a sort of noise blanket and acts as an aid to concentration - by covering more salient noises. The theory is that the brain 'learns' the noise and thus doesn't attend to it. Sounds like you're hacking the hypothesis.

Oh well, it's postmodern world we inhabit?

MA

John Bennett replied on :

Andy wrote:

Hi there,

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD G4 PowerMac? I've finally had enough of the noise - even my housemate's PC over in the other corner of the room doesn't even make HALF as much racket as this thing.

In particular, I'm looking for specific brands/part numbers that worked well so I don't go through the hassle of replacing them for no benefit. Links to Aus suppliers would be greatly appreciated too.

Cheers, Andy. Is it wind or bearing noise? If the latter and it's accessible, a well placed drop of machine oil will likely solve the problem.

PS. Several years ago, some guru found that the noise of fans could be reduced by putting notches in the trailing edge of the blades. It spread the noise over a wider spectrum ("More white") making it seem quieter. I saw some and it seemed to work but the idea never took off.

John

Andy replied on :

Emma Grey wrote:

In article 47078914$0$3589$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

Hi there,

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD G4 PowerMac? I've finally had enough of the noise - even my housemate's PC over in the other corner of the room doesn't even make HALF as much racket as this thing.

In particular, I'm looking for specific brands/part numbers that worked well so I don't go through the hassle of replacing them for no benefit. Links to Aus suppliers would be greatly appreciated too.

Cheers, Andy.

Funnily enough, I actually LIKE the noise of my MDD G4. It's a sort of noise blanket and acts as an aid to concentration - by covering more salient noises. The theory is that the brain 'learns' the noise and thus doesn't attend to it. Sounds like you're hacking the hypothesis.

Oh well, it's postmodern world we inhabit?

Seriously? Did yours have the PS upgrade offered by Apple, though?

This is one of the 'early' models, but unfortunately for me never received the upgrade.

I have to move away from the machine to /take a phone call/ it's that noisy.

Andy.

Andy replied on :

John Bennett wrote:

Andy wrote:

Hi there,

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD G4 PowerMac? I've finally had enough of the noise - even my housemate's PC over in the other corner of the room doesn't even make HALF as much racket as this thing.

In particular, I'm looking for specific brands/part numbers that worked well so I don't go through the hassle of replacing them for no benefit. Links to Aus suppliers would be greatly appreciated too.

Cheers, Andy. Is it wind or bearing noise? If the latter and it's accessible, a well placed drop of machine oil will likely solve the problem.

Could be a bit of both. I'd need to take the PS apart just to get at them anyway, so I'm happy enough to just throw them away.

PS. Several years ago, some guru found that the noise of fans could be reduced by putting notches in the trailing edge of the blades. It spread the noise over a wider spectrum ("More white") making it seem quieter. I saw some and it seemed to work but the idea never took off.

John

Makes sense, just waiting for the fans to arrive so I can see if it makes a serious difference or not.

Cheers, Andy.

Emma Grey replied on :

In article 470b3f60$0$23834$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

Emma Grey wrote:

In article 47078914$0$3589$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

Hi there,

Just wondering if anyone here has ever played with replacing the noisy power supply fans in a MDD G4 PowerMac? I've finally had enough of the noise - even my housemate's PC over in the other corner of the room doesn't even make HALF as much racket as this thing.

In particular, I'm looking for specific brands/part numbers that worked well so I don't go through the hassle of replacing them for no benefit. Links to Aus suppliers would be greatly appreciated too.

Cheers, Andy.

Funnily enough, I actually LIKE the noise of my MDD G4. It's a sort of noise blanket and acts as an aid to concentration - by covering more salient noises. The theory is that the brain 'learns' the noise and thus doesn't attend to it. Sounds like you're hacking the hypothesis.

Oh well, it's postmodern world we inhabit?

Seriously? Did yours have the PS upgrade offered by Apple, though?

This is one of the 'early' models, but unfortunately for me never received the upgrade.

I have to move away from the machine to /take a phone call/ it's that noisy.

Andy.

No retrospective upgrade for mine, but as it's a single processor (3 legged dog) I think that makes it the later MDD model? Maybe I was lucky my money showed up later than expected - as usual. I guess you wish it was the old days when you had a nice black screen with green letters and the mainframe was a few miles away.

Emma :-)

Andy replied on :

Emma Grey wrote:

In article 470b3f60$0$23834$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

Seriously? Did yours have the PS upgrade offered by Apple, though?

This is one of the 'early' models, but unfortunately for me never received the upgrade.

I have to move away from the machine to /take a phone call/ it's that noisy.

Andy.

No retrospective upgrade for mine, but as it's a single processor (3 legged dog) I think that makes it the later MDD model? Maybe I was lucky my money showed up later than expected - as usual. I guess you wish it was the old days when you had a nice black screen with green letters and the mainframe was a few miles away.

Emma :-)

No, but I do miss the silence of my first Macintosh 512Ke!

The fans will be collected tomorrow. Fingers crossed ;-)

Cheers, Andy.

Emma Grey replied on :

In article 470cc20c$0$23809$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

Emma Grey wrote:

In article 470b3f60$0$23834$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

Seriously? Did yours have the PS upgrade offered by Apple, though?

This is one of the 'early' models, but unfortunately for me never received the upgrade.

I have to move away from the machine to /take a phone call/ it's that noisy.

Andy.

No retrospective upgrade for mine, but as it's a single processor (3 legged dog) I think that makes it the later MDD model? Maybe I was lucky my money showed up later than expected - as usual. I guess you wish it was the old days when you had a nice black screen with green letters and the mainframe was a few miles away.

Emma :-)

No, but I do miss the silence of my first Macintosh 512Ke!

The fans will be collected tomorrow. Fingers crossed ;-)

Cheers, Andy.

Hope it works for you.

All the best

Emma

Andy replied on :

Well...to update...they're in.

It's made some difference, but I think I'm going to have to solder a resistor in there somewhere to slow them down a touch.

Thoughts?

Andy.

The New Guy replied on :

Well...to update...they're in. It's made some difference, but I think I'm going to have to solder a resistor in there somewhere to slow them down a touch.

Andy, try not to cut off the previous posts that are obviously relevant. But I'm going to guess that you replaced a fan and now its still loud. Look at the mounting points and see if you feel any vibration. If so, try mounting on rubber or nylon washers. But the real solution for noise with most computers and power supplies is to simply remove the power supply completely from the box, then turn the 80 mm fan around so its blowing in, not out. Then power it from the red and black wires (which will give 5 volts), not the yellow and black wires which give 12 volts. It will run at a much slower speed but since you're using cooler external, room temperature air to cool the power supply heatsink, you don't need to run it at the higher rpm speed from 12 volts. It will be almost inaudible. WAY quieter than at 12 volts.

If that model uses the big 5" fan on the side wall, disable it. Its noisy and useless. Then get an 80 mm or larger fan (whatever size is necessary to cover the CPU heatsink, and run it at 5 volts (red and black wires. To keep the case from heating up, just leave it ajar about an inch. The heat will escape easily. But watch for dust. It might be wise to place it under a shelf as long as there's good ventilation.

Now you'll have a Mac that is almost inaudible and runs way cooler than before. So it should server you far longer than the original design.

Andy replied on :

The New Guy wrote:

Well...to update...they're in. It's made some difference, but I think I'm going to have to solder a resistor in there somewhere to slow them down a touch.

Andy, try not to cut off the previous posts that are obviously relevant.

Err...right. Considering none of the replies were really relevant, that's why I started fresh. Some call it 'netiquette'.

But I'm going to guess that you replaced a fan and now its still loud.

It was somewhat quieter, but not dramatically so. With the resistors in place it's a lot quieter. Still a bit of whine though, some of which is coming from the hard drive as it turns out.

Look at the mounting points and see if you feel any vibration. If so, try mounting on rubber or nylon washers.

That's the next step.

But the real solution for noise with most computers and power supplies is to simply remove the power supply completely from the box,

Not really a solution I'm prepared to attempt.

then turn the 80 mm fan around so its blowing in, not out. Then power it from the red and black wires (which will give 5 volts), not the yellow and black wires which give 12 volts.

?? The power supply in question runs 2 60mm fans side by side, which blow air into the front of the power supply. There are no 'wires' to choose from, merely 2 prong connectors that moulded plastic connectors slide onto.

It will run at a much slower speed but since you're using cooler external, room temperature air to cool the power supply heatsink, you don't need to run it at the higher rpm speed from 12 volts. It will be almost inaudible. WAY quieter than at 12 volts.

I can only assume you've not looked inside a MDD PowerMac.

If that model uses the big 5" fan on the side wall, disable it.

See above.

Its

noisy and useless. Then get an 80 mm or larger fan (whatever size is necessary to cover the CPU heatsink, and run it at 5 volts (red and black wires. To keep the case from heating up, just leave it ajar about an inch. The heat will escape easily. But watch for dust. It might be wise to place it under a shelf as long as there's good ventilation.

No offense, but that sounds like an utterly shithouse solution. The CPU heatsink has a 120mm fan (next on the replacement list) which has it's speed controlled by a temperature sensor.

Andy.

The New Guy replied on :

In article 471051c6$0$23816$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

The New Guy wrote:

Well...to update...they're in. It's made some difference, but I think I'm going to have to solder a resistor in there somewhere to slow them down a touch.

Andy, try not to cut off the previous posts that are obviously relevant.

Err...right. Considering none of the replies were really relevant, that's why I started fresh. Some call it 'netiquette'.

But I'm going to guess that you replaced a fan and now its still loud.

It was somewhat quieter, but not dramatically so. With the resistors in place it's a lot quieter. Still a bit of whine though, some of which is coming from the hard drive as it turns out.

Look at the mounting points and see if you feel any vibration. If so, try mounting on rubber or nylon washers.

That's the next step.

But the real solution for noise with most computers and power supplies is to simply remove the power supply completely from the box,

Not really a solution I'm prepared to attempt.

then turn the 80 mm fan around so its blowing in, not out. Then power it from the red and black wires (which will give 5 volts), not the yellow and black wires which give 12 volts.

?? The power supply in question runs 2 60mm fans side by side, which blow air into the front of the power supply. There are no 'wires' to choose from, merely 2 prong connectors that moulded plastic connectors slide onto.

It will run at a much slower speed but since you're using cooler external, room temperature air to cool the power supply heatsink, you don't need to run it at the higher rpm speed from 12 volts. It will be almost inaudible. WAY quieter than at 12 volts.

I can only assume you've not looked inside a MDD PowerMac.

If that model uses the big 5" fan on the side wall, disable it.

See above.

Its

noisy and useless. Then get an 80 mm or larger fan (whatever size is necessary to cover the CPU heatsink, and run it at 5 volts (red and black wires. To keep the case from heating up, just leave it ajar about an inch. The heat will escape easily. But watch for dust. It might be wise to place it under a shelf as long as there's good ventilation.

No offense, but that sounds like an utterly shithouse solution. The CPU heatsink has a 120mm fan (next on the replacement list) which has it's speed controlled by a temperature sensor.

Andy.

As you wish. I've done it and it results in a near silent system running much cooler.

Andy replied on :

The New Guy wrote:

Its

noisy and useless. Then get an 80 mm or larger fan (whatever size is necessary to cover the CPU heatsink, and run it at 5 volts (red and black wires. To keep the case from heating up, just leave it ajar about an inch. The heat will escape easily. But watch for dust. It might be wise to place it under a shelf as long as there's good ventilation.

No offense, but that sounds like an utterly shithouse solution. The CPU heatsink has a 120mm fan (next on the replacement list) which has it's speed controlled by a temperature sensor.

Andy.

As you wish. I've done it and it results in a near silent system running much cooler.

OK, just as a further update - the bulk of the noise (I'd guess about 90%) is now coming from the OE IBM Hard Drive. A 160GB Seagate Barracuda has been ordered to replace it. The original drive will be used for a monthly back up, but remain otherwise unplugged.

And further to the initial response - the case has no problems with overheating. In 'Nap' mode the processors sit at about 38 degrees C under light/normal use. I'll still look to replace the 120mm fan however, likely with something from Panaflo.

Cheers, Andy.

Emma Grey replied on :

In article 471051c6$0$23816$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

The New Guy wrote:

Well...to update...they're in. It's made some difference, but I think I'm going to have to solder a resistor in there somewhere to slow them down a touch.

Andy, try not to cut off the previous posts that are obviously relevant.

Err...right. Considering none of the replies were really relevant, that's why I started fresh. Some call it 'netiquette'.

Ahem, New Guy - if you're a New Guy and thus self-confessedly are not fully acquainted with this thread - let alone this group - you might well consider making your entry with just a little politeness. There are simple ways of checking the full thread of an article, and if you choose not to bother with this, then I suggest you give consideration to the limitations you have opted to apply, and criticise others in such a blunt and ill-informed fashion.

For your information, this thread took a side turning with my suggestion that I found the noise of my MDD to be quite useful in blocking other more salient noises. Thus it was entirely appropriate to trim the original post.

Why not lurk for a bit longer and learn how this group operates before hoofing in and making an ... [noun trimmed] ... of yourself.

Emma

Andy replied on :

Emma Grey wrote:

In article 471051c6$0$23816$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

The New Guy wrote:

Andy, try not to cut off the previous posts that are obviously relevant.

Err...right. Considering none of the replies were really relevant, that's why I started fresh. Some call it 'netiquette'.

Ahem, New Guy - if you're a New Guy and thus self-confessedly are not fully acquainted with this thread - let alone this group - you might well consider making your entry with just a little politeness. There are simple ways of checking the full thread of an article, and if you choose not to bother with this, then I suggest you give consideration to the limitations you have opted to apply, and criticise others in such a blunt and ill-informed fashion.

For your information, this thread took a side turning with my suggestion that I found the noise of my MDD to be quite useful in blocking other more salient noises. Thus it was entirely appropriate to trim the original post.

Why not lurk for a bit longer and learn how this group operates before hoofing in and making an ... [noun trimmed] ... of yourself.

Emma

Hi again Emma,

I'd suspect he won't actually read your reply, as he was likely responding from comp.sys.mac.hardware (where I initially crossposted to).

Unfortunately, he's far from being a 'new guy', and has some rather....'interesting' ideas on Mac cooling. Nearly every post from him revolves around installing massive heat-sinks and having e-SATA plugs hanging out of the back of Mac Minis - Almost as much use as the advice given in this thread about removing the power supply completely from the machine and running with the side door 'just open' to keep it cool.

I'm getting nearer to a solution, anyway. While the machine will never be 'silent', I think the replacement of the horrendously noisy hard drive will remove a large portion of the whining noise from my 'old faithful' MDD machine. On that note, I'll be interested to see how it handles Leopard in month or two time.

Thanks again, take care.

Andy.

Emma Grey replied on :

In article 4711945b$0$11577$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

Emma Grey wrote:

In article 471051c6$0$23816$5a62ac22@redacted.invalid, Andy nospam@redacted.invalid wrote:

The New Guy wrote:

Andy, try not to cut off the previous posts that are obviously relevant.

Err...right. Considering none of the replies were really relevant, that's why I started fresh. Some call it 'netiquette'.

Ahem, New Guy - if you're a New Guy and thus self-confessedly are not fully acquainted with this thread - let alone this group - you might well consider making your entry with just a little politeness. There are simple ways of checking the full thread of an article, and if you choose not to bother with this, then I suggest you give consideration to the limitations you have opted to apply, and criticise others in such a blunt and ill-informed fashion.

For your information, this thread took a side turning with my suggestion that I found the noise of my MDD to be quite useful in blocking other more salient noises. Thus it was entirely appropriate to trim the original post.

Why not lurk for a bit longer and learn how this group operates before hoofing in and making an ... [noun trimmed] ... of yourself.

Emma

Hi again Emma,

I'd suspect he won't actually read your reply, as he was likely responding from comp.sys.mac.hardware (where I initially crossposted to).

Yep, I wondered about that when I trimmed the cross-posting in my reply. Never mind. Even if he did literally read it, that sort of mentality doesn't usually comprehend anything it don't want to see.

Unfortunately, he's far from being a 'new guy', and has some rather....'interesting' ideas on Mac cooling. Nearly every post from him revolves around installing massive heat-sinks and having e-SATA plugs hanging out of the back of Mac Minis - Almost as much use as the advice given in this thread about removing the power supply completely from the machine and running with the side door 'just open' to keep it cool.

Yes I loved that one! It made me suspect he was about to suggest a water-cooled Mac with an energy exchange system to heat the pool. Or a fan under the house with ducting?

I'm getting nearer to a solution, anyway. While the machine will never be 'silent', I think the replacement of the horrendously noisy hard drive will remove a large portion of the whining noise from my 'old faithful' MDD machine.

Years ago I owned a recording studio, and - first time powering up after an upgrade - for a moment I thought nothing was working. It was silent! No hum, no hiss - no signs of life at all!

On that note, I'll be interested to see how it handles Leopard in month or two time.

Ah, the new cat. It's so long since everyone got bored with waiting for it I'd quite forgotten. Let's hope its purr isn't too loud for you.

All the best

Emma

Andy replied on :

On 23/10/07 9:02 PM, Mogens V. wrote:

Though I have no idea if they can be bought anymore, I can recommend Mist Frostbite 120mm fans. Else I'll most likely use these:

http://studiedata.dk/shop/noctua-nf-s12-800-blaeser-6024p.html http://studiedata.dk/shop/noctua-nf-s12-1200-blaeser-5993p.html

Yup, danish, so a few explanations; CFM/dBa.. should be understandable. They feature SSO-bearings (Self Stabilizing Oil pressure bearings). The dBa ratings are with/without the noise adaptor thingy.

Hmmm....I'm not sure that they'll be suitable for CPU cooling duties. The stock fan pushes 108CFM peak. I've purchased one that pushes 86.5cfm peak and I'm currently running it at a constant 7 volts (I fried the temperature controlled fan plug on the motherboard). It's not quite enough cooling (running in 'Nap' mode is fine though), I added a 60mm fan inside the back of the case (there's a recess that's an absolutely perfect space to fit it so it sucks air across the heatsink) but I'll need to run them through a fan controller at around 8-9 volts to get sufficient cooling happening (approaching summer here). I've also removed the plastic covers on the back of the machine entirely to reduce turbulence for air exiting the unit.

I'm about shopping them for my G4 dual 800, plus doing something about the noisy cpu fan/duct, which I believe is a mix of the actual fan plus the hissing noise produced by the smallish duct ending in a grill on the rear of the box. Had it been a PC I'd simply cut that grill off.. Dunno yet which fan I'll use for the PSU.

Trust me, the 60mm PSU fans are the main problem. I bought replacements that push slightly less air than stock but with a better dB rating, but they're still pretty noisy. I tried a 47 Ohm resitor, which quietened them /slightly/, but I wasn't convinced the PSU was getting adequate cooling (to be blunt I was fairly certain it wasn't, as I couldn't feel any air exiting the back of the case).

If I can be bothered (I've had the power supply apart 4 times now) I'm going to look at making something some kind of adaptor device so I can run 80 or 92mm fans at a much lower speed into the PSU.

If you find genuinely quiet 12V 60mm fans, please, please let us know :-)

Cheers, Andy.

Mogens V. replied on :

Andy wrote:

The New Guy wrote:

Its

noisy and useless. Then get an 80 mm or larger fan (whatever size is necessary to cover the CPU heatsink, and run it at 5 volts (red and black wires. To keep the case from heating up, just leave it ajar about an inch. The heat will escape easily. But watch for dust. It might be wise to place it under a shelf as long as there's good ventilation.

No offense, but that sounds like an utterly shithouse solution. The CPU heatsink has a 120mm fan (next on the replacement list) which has it's speed controlled by a temperature sensor.

Andy.

As you wish. I've done it and it results in a near silent system running much cooler.

OK, just as a further update - the bulk of the noise (I'd guess about 90%) is now coming from the OE IBM Hard Drive. A 160GB Seagate Barracuda has been ordered to replace it. The original drive will be used for a monthly back up, but remain otherwise unplugged.

And further to the initial response - the case has no problems with overheating. In 'Nap' mode the processors sit at about 38 degrees C under light/normal use. I'll still look to replace the 120mm fan however, likely with something from Panaflo.

Cheers, Andy.

Though I have no idea if they can be bought anymore, I can recommend Mist Frostbite 120mm fans. Else I'll most likely use these:

http://studiedata.dk/shop/noctua-nf-s12-800-blaeser-6024p.html http://studiedata.dk/shop/noctua-nf-s12-1200-blaeser-5993p.html

Yup, danish, so a few explanations; CFM/dBa.. should be understandable. They feature SSO-bearings (Self Stabilizing Oil pressure bearings). The dBa ratings are with/without the noise adaptor thingy.

I'm about shopping them for my G4 dual 800, plus doing something about the noisy cpu fan/duct, which I believe is a mix of the actual fan plus the hissing noise produced by the smallish duct ending in a grill on the rear of the box. Had it been a PC I'd simply cut that grill off.. Dunno yet which fan I'll use for the PSU.