I read on tom's hardware comparison chart, and other sources, that the 9800 GT 512 MB was slightly faster than the XFX 8800 GTS 640MB.
However I have noticed that when I start a certain game that for about .5 sec it has LOW fps and then boosts itself up without any problems once the match has been started. I have also been unable to run the new "Aliens versus Predator" with everything maxed out like my old card. During movie cutscenes it runs very very smoothly but then freezes and slowly goes through it frame by frame almost, while it cant catch up with the sound playing. The card runs 60C idle, probably 70-80C in a game with fan speed only being set to default 5%.
I just got this card yesterday and it runs fairly quiet. However i've noticed that if im slowly scrolling down my web browser, I can hear this faint noticable noise coming from my video card. It sounds like a little fan running only when I scroll down in my web browser.
Any advice or opinions on the 9800 GT 512 MB vs the XFX 8800 GTS 640 MB? How would one safely overclock this to match my old 8800 GTS?
More aboutnvidia 9800 issues
the 9800GT is a faster the the 8800GTS 640mb (the 8800GTS 512mb version is a completely different card)
your temps are inline with a stock 8800GT/9800GT. run gpu-z to make sure the card runs at stock speeds. You may have a bad card.
What about driver? Did you install the latest one?
GPU Default clock speed is at 550. Currently at my desktop the sensors are saying its at 300. Yes I do have the latest drivers. During games it gets to 540 at the moment for the GPU core clock and 900 to the memory clock.
The AvP issue is something to do with the game I think as I have the same issue and so do a couple of buddies with ATi cards.