Don't know about KV8 PRO, but I have just spent a frustrating couple of
hours making my new 6600GT work. The system would always boot, but
running benchmarks or games would some of the time reduce the framerate
to a slide show, other times would run fine with no apparent pattern.
Then, after a while, the system would hang every time after logging into
Windows.
Was just about to give up and replace the card with an old MX400 from
the spares box when I tried plugging the power connector into a
different cable from the PSU - hey presto! Every suddenly works like a
dream
Could be worth a try if you are having problems. The 6600GT seems fussy
about power as my previous card, a Radeon 9700 Pro was plugged into the
same power lead (with an adapter of course) and never had a problem.
Ian