I should imagine that the last one you set the clock on will be the
overriding one, for example if you clocked it at 280 in coolbits, then 300
in EXPERTool, it would run at 300, and vice-versa.

I would say at 320/675 you're going to be lucky to not damage the card or
get artifacts, but in all cases YMMV.

Clock it up 5MHz at a time, and run some tests for an hour or so, if its
ok,
push it a bit further. Slow and tedious I know, but better than pushing it
waaaay to far when you start off.

Thanks for the reply. I've had the card for about 15 months, love it. I've
never messed with OC'ing prior to now because I didn't need it.

I'm getting 19 fps in 1024x768 and 25 fps in 800x600 playing Doom. That's
prior to any tweaks. It could be better, but it is certainly playable.