I have adjusted them, I pushed the memory and processor to max before artifacts would appear.  That gave me a bit more- but it seems to max out at 550 and seems to just want to chug along at 48-500.

It's sitting in a PCI-E x16 2.0 slot on a 3.0 C2D system (I had it laying around).

It's a HIS card, do you guys think that's what the performance is due to- would I have better luck with a MSI, ASUS, or other better brand?