Why 20% minimum GPU fan speed (reference cooler 5850)

[KingFatty]

Hi all,

I'd like to *reduce* the idle fan speed of my reference 5850 to less than 20%, to make less noise.

I don't mind allowing the card to run a little warmer and I'm fine making a custom profile to reduce the idle speed to say 8% when the temps are acceptable at idle.

However, are there any other hidden dangers? Example: would the fan mechanically suffer if run at a slower speed most of the time? Is the default 20% minimum done for any other mechanical benefits? I know with some gasoline engines it's suggested to run them a certain way, so maybe some of that is applicable to electrical motors/brushes/bearings? Are GPU engineers choosing the default idle fan speeds due to something besides GPU heat/performance, such as according to some hidden specs for the electrical motor and average life expectancy based on average RPM speed where too-low might be sub-optimal?

I had an old trusty Nvidia 6600 GT way back when and its fan failed, so maybe I'm over-compensating for getting *burned* (get it?) in the past regarding GPU fans. Not to mention I had a motherboard fan go out on my trusty old ASUS A8N-SLI Deluxe mobo many years ago. That tiny little fan burned its little heart out spinning like mad, oh so tiny...

 

[Sunny129]

i'm no expert, but i believe its a parameter that's hard coded into the BIOS of your particular card (or perhaps all reference 5850's...i don't know). i have a Galaxy GT 430 who's fan cannot be adjusted below 50%, so i just disconnected the fan from the header on the PCB to keep it from sounding like a leaf blower. temps never get out of control b/c i don't ever game with it.

 

[Phynaz]

Are you sure you can hear the fan at 20%, and it's not some other noise?

 

[ZipSpeed]

Are you sure you can hear the fan at 20%, and it's not some other noise?

Indeed. I can't hear my 5850 at 20%.

 

[Sunny129]

i no longer have the blower-style reference cooler on my 5870 b/c it was too loud at any fan speed above 35%. but when the card would idle and the fan speed was on auto, it would fluctuate between 20-22% and was virtually silent. while i can't say this with 100% confidence, i seem to recall that i was also unable to drop the fan speed below 20%. granted we had to different cards, but mine was a reference design too.

 

[VirtualLarry]

I can't even hear my GTX460 at 70% fan speed. LOL.

(Gigabyte dual-fan Windforce card)

 

[Sunny129]

I can't even hear my GTX460 at 70% fan speed. LOL.

(Gigabyte dual-fan Windforce card)

there's quite a difference between the blower-style reference cooler that the OP is talking about and the dual fan non-reference cooler on your GTX 460 . of course what you claim about that style of cooler is expected - i first replaced the reference cooler on my 5870 with an Arctic Cooling Twin Turbo Pro dual fan cooler, and later upgraded to the Arctic Cooling Twin Turbo II dual fan cooler. both of them were silent (even with the fan speed as high as 100%) compared to the blower-style reference cooler (even with the fan speed as low as 30%) that came with the card...

...of course the most important thing we should all take away from this conversation is that, as more and more people comment here, the more obvious it becomes that noise is quite subjective - what one person finds to be a completely acceptable volume level someone else may find unbearably loud.

 

[Termie]

Hi all,

I'd like to *reduce* the idle fan speed of my reference 5850 to less than 20%, to make less noise.

I don't mind allowing the card to run a little warmer and I'm fine making a custom profile to reduce the idle speed to say 8% when the temps are acceptable at idle.

However, are there any other hidden dangers? Example: would the fan mechanically suffer if run at a slower speed most of the time? Is the default 20% minimum done for any other mechanical benefits? I know with some gasoline engines it's suggested to run them a certain way, so maybe some of that is applicable to electrical motors/brushes/bearings? Are GPU engineers choosing the default idle fan speeds due to something besides GPU heat/performance, such as according to some hidden specs for the electrical motor and average life expectancy based on average RPM speed where too-low might be sub-optimal?

I had an old trusty Nvidia 6600 GT way back when and its fan failed, so maybe I'm over-compensating for getting *burned* (get it?) in the past regarding GPU fans. Not to mention I had a motherboard fan go out on my trusty old ASUS A8N-SLI Deluxe mobo many years ago. That tiny little fan burned its little heart out spinning like mad, oh so tiny...

Electric motors, including fans, typically need a minimum voltage just to turn. It's possible that the 20% fan speed corresponds with the minimum operating voltage of the 5850 fan.

And no, I've never found any option to reduce my reference 5850 below 20%, and I doubt you will either. It's very quiet at that speed, although I'll admit that it's not silent.

 

[KingFatty]

I could have sworn I saw in MSI Afterburner the ability to set a custom fan profile that allowed me to set the RPMs below 20%, or is it impossible to do this *without* using Afterburner (or does Afterburner just lie to me)?

As far as noise, the fan is I think getting ready to die on me, where it will sometimes make a groaning sound at 20%. If I crank up the speed manually to hear the blowdryer sound, the groaning sound goes away and usually stays away even when i drop the speed back down to 20%. Without the groaning sound, 20% is very quiet and i'm fine with that level of noise. But that's annoying to jump through hoops to make the groaning go away, and I swear I remember the groaning sound going away when i used Afterburner to drop the fan speed below 20%?

I'm going to milk this fan as long as I can, and hopefully the groaning is just something that won't get worse. Groaning is an exaggeration, but it's a different light rumbling sound compared to the typical whirring/blowdryer sound normally associated with reference blowers.