Radeon 4870 x2 odd jerkiness

Mobo: ASUS P6T Intel X58
CPU: Intel Core i7 920
RAM: Corsair XMS3 6 GB (3 x 2 GB) DDR3
GPU: Sapphire ATI Radeon 4870 x2 (hot hot hot!)
HDD: Western Digital Caviar Black 1 TB 7200 RPM
PSU: Antec Earthwatts EA 750
Case: Antec Nine Hundred
OS: 64-Bit Windows Vista SP 2
Video Driver: Catalyst 9.10

I have had this custom-built system since mid-May 2009. Performance overall has been very good; 9/10 I'd say. However, the video card seems to perform strangely at times.

There is a jerkiness to motion, but it can't be described as low FPS. My FPS is very good for the most part. It's almost as if the high FPS framerate isn't steady. I've noticed this oftentimes in Fallout 3, Call of Duty 4, Crysis, and Portal. In Fallout and Call of Duty, motion is jerky depending on what is happening on the screen. In Crysis, the FPS drops significantly when I swing the view around quickly and their fancy motion blur kicks in. Of greatest concern: In Portal, the sequence at the end of the final test chamber when you are about to be dumped in the fire pit the jerkiness intensifies tenfold, as well as in Call of Duty 4 during the nuke aftermath as you climb out of the helicopter. Clearly, the card seems to behave most oddly when rendering scenes with very high particle counts, which is strange given the fact that the card is (or was until recently) state-of-the-art. The 3DMark Vantage particle test also slowed to a near standstill.

Now to complicate things, ever since day 1, whenever I boot up a game and the video card kicks it into high gear, I hear this awful high pitched whining. It's not loud, but it's definitely there, and the frequency and humming of the sound correspond directly to what's happening on the screen. At first I was concerned it was the video card, but I am certain now that it is the PSU. When rendering scenes with high particles as I mentioned before, the pitch of the whining fluctuates at exactly the same rate as the jerkiness.

This seems odd to me, having read about issues of not having enough power for multiple beefy 4870 x2s in Crossfire mode. But I only have one running alone, and with a 750 Watt PSU, I figured it would be more than enough power. The PSU has two +12V rails, and the second rail is occupied only by the video card.

Is the likely solution to my problem simply to jump on my PSU's 3-year warranty? I honestly assumed the noises were the thing being broken in, but almost six months later, I'm beginning to wonder. Or are my jerky framerate woes not the PSU at all and something else? I've used every iteration of the Catalyst drivers since whatever version was out in May in every conceivable mode: AI on, AI off, FSAA at 0, FSAA at 4, resolution at 1024x768, resolution at 1920x1080, etc.

Any insight anyone can offer would be greatly appreciated!
1 answer Last reply
More about radeon 4870 jerkiness
  1. Micro-stutter for Xfire/SLi

    It's more noticeable in some games/some situations I guess...

    Or it could be driver issues...if you ever had Nvidia drivers, download drive-sweeper and clean out your harddrive.
Ask a new question

Read More

Graphics Cards Graphics