It'll vary with every card but it could be 250mhz. The Ultra runs at 250mhz- but they use the best GPU's to achieve those high clock speeds. If your lucky you can get 250mhz but 240mhz is more likely. The RAM is a different story- it depends on that access time (5ns, 5.5ns, etc). If the access time is 5ns you could probably get 450mhz with little problems.
-MP Jesse
"Signatures Suck"