I recently upgraded to a Radeon 4890 graphics card, and when I installed, my CPU usage is at 100%. I was orginally running a very much lower card (think 128mb card) and this one is seeming to be MUCH slower. I was running Windows 7 64bit, and after trying drivers on the cd and the most recent ones from the ATI website, nothing would help. I have done a fresh install of Windows 7 (32 bit this time), and have installed the most recent and correct drivers from the ATI website. I can have almost othing running and still have 100% CPU usage. I have also checked everything that is running in the background, and all the svchost processes and it is not running anything that it is not supposed to. I'm running with a AMD Athalon 64 with 3gb of ram.
It varied from time to time. Sometimes it was an svchost, sometimes firefox, sometimes an installer. At this very moment, it is internet explorer (which I am using to type this) using 73,460 K. There are only 9 other things listed, only 2 which are above 10,000 K. (svchost is not even listed right now as this is a fresh install). Under the 'CPU' category, everything is 00, except iexplore and taskmgr sometimes blink up to 25, but never higher.
CPU still says 100% (sometimes drops into the 90's, but never lower) and Physical Memory Usage stays around 500MB.
defective card that fires constant interrupt requests to the CPU?
I've never heard of such a defect but i suppose its possible. considering you've done a reinstall of windows I can't imaging there is anything in software which is causing this. It seems to be a hardware defect. If no one can come up with a good explanation I would say you will have to RMA.
Well, I went from win 7 (64) to win 7 (32), both had issues, and now I have installed Win XP, and have no issues with it now. Runs fine. I've googled a lot and found other people with these issues with Win 7, but they all seem to be issues with random things, and not just the graphics card (and most all seem to be driver issues).
I don't really feel its a hardware issue, and maybe one day in the future I will upgrade back to win 7 once ATI fixes these drivers.