Hey tejas, I recently bought two of these bad boys, wow they dropped about $30 since I bought them a month ago:
and I'm very happy with them. I can overclock them to about 710, but I put them back to 680Mhz cause I was see some artifacting after about 30mins. I also now run the fans about 80-90% just when playing games...
I get about 40-50fps in crysis at 1920x1200 in high/very high mode using the natural mod and mstrconfig (sp?) 3.1... every other games runs 60+ fps with everything else turned on... Oblvion dips under 60fps and there are slight pauses about every 30-90s but when I drop down to 1 card I still get the pauses with decent fps so I'm pretty sure it's load times or something else wrong... no other games micro stutters at all, Grid, bioshock, fallout3, farcry2 and COD4 are all very smooth...
so I'd say for the price/performance I think they are the best value, just make sure your PSU is big enough to handle them:
SLI Power supply/Consumption requirements