[geeks] Of video cards and power supplies...

[Lionel Peterson]

On Jul 14, 2009, at 5:46 PM, nate at portents.com wrote:

> Since I know some of you have expressed interest in quiet systems, I
> thought I would share the following experiences...
>
> Summary:
> Due to a poor power design in reference NVIDIA cards such as the GTX  
> 280,
> audible squealing and other noises can be emitted from some  
> perfectly good
> power supplies during certain types of GPU load.  ATI cards that use
> digital VRMs such as the HD4850 and HD4870 do not cause any noise to  
> be
> emitted.  I have found that changing the power supply to a design that
> derives the 5V and 3.3V from the 12V in a highly efficient DC to DC
> conversion process, and probably provides greater 12V rail isolation,
> eliminates the noise that a GTX 280 would normally cause.
>
> Details:
> Originally I had a Corsair HX620W power supply, which is a good power
> supply, as detailed in these reviews here:
>
> http://www.hardwaresecrets.com/article/371
> http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=21
>
> It's based on a Seasonic S12 design, and the biggest design flaws  
> are that
> when the there's a high (39A) load on the 12V rail 12V2 and 12V3  
> have a
> total swing of 100mV, which is a bit high, and the power supply  
> doesn't
> have true separation of three 12V rails, which means that noise from  
> one
> 12V rail can affect the others (basically they are virtual rails at  
> best).
>
> Initially I used this power supply with a pair of ATI HD4850 cards,  
> and
> later a pair of HD4870 cards, both of which use Volterra digital  
> VRMs in
> their power design, and there were no unusual sounds coming from my  
> system
> during any GPU workload.  Then I got a single GTX 280, and during  
> certain
> workloads (most often the main menus and load screens of many games  
> and 3D
> benchmarks), very audible sounds were emitted from the power supply.
>
> Some sites have documented this as a problem that can be solved by
> phsyically securing the analog power components to the GTX 280, such  
> as
> this site:
>
> http://theovalich.wordpress.com/2008/11/24/nvidias-deadly-flaw-and-how-to-fix-it-no-more-gtx280-squealing/
>
> However in my experience the sounds were coming from the power  
> supply, as
> described here:
>
> http://www.bit-tech.net/news/hardware/2009/05/29/msi-solves-the-nvidia-gtx-squealing-problem/1
>
> If I had an O-scope, I would certainly like to corroborate Bit-Tech's
> claim about interference going from the graphics card to the power  
> supply:
>
> "After reporting the problem to Nvidia, we were greeted with denial  
> - it
> was unable to replicate the problem - until we sent readouts from an
> oscilloscope, displaying the interference shooting back up the PCIe  
> power
> connectors into the PSU."
>
> Anyway, I theorized that I could eliminate the sounds by getting a
> different power supply, rather than replacing my graphics card or  
> voiding
> its warranty trying to 'fix' it.  After some research, I settled on  
> a DC
> to DC design by Delta that's packaged by Antec as the Signature 650,
> reviewed here:
>
> http://www.hardwaresecrets.com/article/658
> http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=113
>
> With test results that showed ripple and noise below 16mV on all  
> rails in
> jonnyguru's tests, I had hope that this extremely clean and capable  
> design
> would solve the problem.  I doubted that Corsair or BFG - the  
> company that
> branded the NVIDIA reference design GTX 280 - would do anything  
> about a
> design flaw that NVIDIA is at fault for, after all.
>
> In my experience thus far, the Antec Signature 650 has not  
> demonstrated
> any squealing with the GTX 280, and I wouldn't be surprised if other  
> high
> quality DC-DC designs such as the Enermax Revolution and Seasonic M12D
> also cope well with badly-designed cards such as the NVIDIA GTX 280.
>
> Alternatively, you could also avoid the problem by using a recent ATI
> card, using a non-reference designed NVIDIA graphics card, or wait  
> until
> NVIDIA will (most likely) adopt a digital VRM solution like Volterra  
> in
> their future reference designs.

In other words, the nVidia card put an unexpected load on the PS, a  
load that a differently-designed PS could handle?

Personally, I would have avoided a PS by Corsair, my personal  
experience with Supermicro-supplied PS and Antec PS (both bundled with  
chassis and sold retail) have proven themselves as 'known Good Enough'  
PS and I stick to them whenever practical.

I appreciate quiet as well, but I think I would have up-sized the PS  
as my first response[0], I never would have gotten that deep into it,  
but I'm glad you did, and thanks for sharing.

Lionel

[0] to borrow a line from Tim "The Toolman" Taylor[1]- "More Power!  
argh, argh, argh!"

[1] From the TV[2] show Home Improvement

[2] Seriously? ;^)