[geeks] Of video cards and power supplies...
lionel4287 at gmail.com
Tue Jul 14 17:49:30 CDT 2009
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...
> Due to a poor power design in reference NVIDIA cards such as the GTX
> 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
> 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.
> Originally I had a Corsair HX620W power supply, which is a good power
> supply, as detailed in these reviews here:
> 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
> have true separation of three 12V rails, which means that noise from
> 12V rail can affect the others (basically they are virtual rails at
> Initially I used this power supply with a pair of ATI HD4850 cards,
> 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
> during any GPU workload. Then I got a single GTX 280, and during
> 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
> this site:
> However in my experience the sounds were coming from the power
> supply, as
> described here:
> 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
> "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
> 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
> 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:
> 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
> 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
> any squealing with the GTX 280, and I wouldn't be surprised if other
> 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
> NVIDIA will (most likely) adopt a digital VRM solution like Volterra
> 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, I never would have gotten that deep into it,
but I'm glad you did, and thanks for sharing.
 to borrow a line from Tim "The Toolman" Taylor- "More Power!
argh, argh, argh!"
 From the TV show Home Improvement
 Seriously? ;^)
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