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View Full Version : Anyone turned off PCI bay fan in PowerMac G5?


forumBuddy
Oct 21, 2005, 10:58 AM
So basically I have ATI 800XT card in my G5 which besides the wireless card is the only one sitting in the PCI bay. Yet PowerMac's PCI area fan is spinning quite fast just because instead of temperature reading its speed is based on PCI current draw. That makes sence of fanless cards like 9600 but not much for active cooling systems that cards like 800XT have. So has anyone disconnected that fan to quiet down their systems a bit?

I'm thinking about monitoring my temperatures and then disconnecting it and see how it works.

jared_kipe
Oct 21, 2005, 11:35 AM
So basically I have ATI 800XT card in my G5 which besides the wireless card is the only one sitting in the PCI bay. Yet PowerMac's PCI area fan is spinning quite fast just because instead of temperature reading its speed is based on PCI current draw. That makes sence of fanless cards like 9600 but not much for active cooling systems that cards like 800XT have. So has anyone disconnected that fan to quiet down their systems a bit?

I'm thinking about monitoring my temperatures and then disconnecting it and see how it works.

You know, in theory I could do this too. I have a 9800pro with an artic silencer on it. The silencer blows its air directly out the back of the G5, so there is probably little reason for the PCI fan to be on. But I never notice the PCI fan is on, so maybe yours is more of a problem.

alexprice
Oct 21, 2005, 12:40 PM
So basically I have ATI 800XT card in my G5 which besides the wireless card is the only one sitting in the PCI bay. Yet PowerMac's PCI area fan is spinning quite fast just because instead of temperature reading its speed is based on PCI current draw. That makes sence of fanless cards like 9600 but not much for active cooling systems that cards like 800XT have. So has anyone disconnected that fan to quiet down their systems a bit?

I'm thinking about monitoring my temperatures and then disconnecting it and see how it works.

I would strongly advise NOT to disconnect the fan. I once accidently left our showrooms machine's G5 PM PCI fan disconnected. About a month later I noticed what i'd done and connected it back up. Now when its connected that fan runs at full speed all the time. I have left is disconnected as fixing it would require a new logic board from what I managed to work out.

forumBuddy
Oct 21, 2005, 02:02 PM
I see no reason why all of a sudden fun would run full speed. Are you sure it's actually running full speed - or you think it's running full speed? Also have you added any new cards since disconnecting fan that might've increased current draw? I also know that after certain Mac OS version , Apple had to update fan control application because high performance cards like 800XT and NVIDIA would draw current not accounted for before, causing PCI fan run full blast.

Bad_JuJu
Oct 21, 2005, 08:02 PM
I'm an ex-PC designer for Intel - never been inside a PowerMac - fans are used for one 3 reasons
- To bring cool air into the chassis
- To keep air moving inside the chassis ( this I believe is due to poor air-flow design)
- To exhaust warm air from the system

A properly designed system should at a minimum have an exhaust fan - ample intake venting and maybe some local fans on the cpu or gfx card.


Not sure how much you want to fiddle with this -- but one way we found to reduce fan noise is to use 2 fans (side by side) - but have them run at 1/2 speed (thats about 7v for a 12v fan). Example: you have a system with a 900cfm fan - one fan running at full blast (12v) gives you 900cfm but at 42db. You run 2 900cfm fans side by side but reduce the max voltage to 7v -- you still get 900cfm ( 450 x2) but the total noise is now about 33-35db.


The other issue is sound pitch - our work found that the larger the fan the lower the pitch ----- 70mm fans seemed to be the most annoying - 90mm fans were the sweet spot

Bear
Oct 22, 2005, 06:05 AM
...
A properly designed system should at a minimum have an exhaust fan - ample intake venting and maybe some local fans on the cpu or gfx card.
...The PowerMac G5 has several fans. The cooling was designed so the fans could spin slower.

As for the original question, do not disable any fans, it makes sure that the heat in that section gets moved out of the computer. Yes, the card can have a fan on it, but where will it get cool air from if you disable the fan in that section? Also, no section is totally thermally isolated from each other, so you'd be impacting the disk drives above the video board by the heat that is no longer being pushed outside the computer. And there would be heat from the processors that would now not be pushed out.

Disabling the fan is a bad idea and also could void any warranty you may have left. If you have any warranty (or AppleCare) on the computer, talk with Apple and let them know the fan is making a lot of noise. The fan speed is driven by thermal sensors - you could have a bad sensor.

alexprice
Oct 22, 2005, 07:01 AM
I see no reason why all of a sudden fun would run full speed. Are you sure it's actually running full speed - or you think it's running full speed? Also have you added any new cards since disconnecting fan that might've increased current draw? I also know that after certain Mac OS version , Apple had to update fan control application because high performance cards like 800XT and NVIDIA would draw current not accounted for before, causing PCI fan run full blast.
Nothing else changed, I assure you the PCI fan alone was running at full speed, it was really loud.

Kyle Nerder
Nov 13, 2005, 10:18 AM
Mine too! My PCI card section fan runs at full rpm. I am only running a ATI Radeon X800 256mb. This machine would be whisper quiet if it wasn't for that. DO I have any options on shutting this thing up?

Kyle Nerder
Nov 13, 2005, 08:28 PM
turns out my noise isn't the pci bay fan. It's the vid card. ATI Radeon X800. Anyone know how to shut that fan up? or does that fan have 1 set constant rpm. fast and lound.

Maybe I'll trade with someone...

Kyle Nerder
Nov 13, 2005, 08:52 PM
cancel that. I found a driver on ATI's site and it's perfect now.....

Surpisingly I didn't see this anywhere else on the forum. I saw Apple firmware updates, but I was up to date.

Eric5h5
Nov 13, 2005, 09:36 PM
Apple certainly did something with the PCI bay fan (I think) after 10.3.7. Namely, it's really annoying with an X800 in there, and it's not the X800 fan. It's a little louder, but the big problem is that the pitch varies randomly, which is the really annoying part. I wouldn't mind if it was louder but just stayed at one pitch. I normally use 10.3.7 just because of that. I really wish Apple would go back to whatever they did with 10.3.7, or at least have that option. I reported this back in 10.3.8 but nothing has changed since then. Are there any fan control hacks out there?

--Eric

Kyle Nerder
Nov 14, 2005, 08:19 AM
Apple certainly did something with the PCI bay fan (I think) after 10.3.7. Namely, it's really annoying with an X800 in there, and it's not the X800 fan. It's a little louder, but the big problem is that the pitch varies randomly, which is the really annoying part. I wouldn't mind if it was louder but just stayed at one pitch. I normally use 10.3.7 just because of that. I really wish Apple would go back to whatever they did with 10.3.7, or at least have that option. I reported this back in 10.3.8 but nothing has changed since then. Are there any fan control hacks out there?

--Eric
I am currently running OS 10.4.3 . And it is much better then 10.3 . Well worth the purchase. I never ran 10.3 on this machine, but it was noisy (vid card fan noise) from the second I bought it. OS updates didn't seem to make a difference. I researched the problem until I found a fix. ATI has a driver firmware update for that vid card. Now the fan runs at a slow rpm and kicks in with intensive video needs. The firmware required me restart the computer in SAFE mode and then install and then reboot.

This made such a difference that I was able to sleep with the machine on last night!