since i got anohter 7800gt for matching sli, my rig, 300x9 with 1.45v, have been getting lots of trouble with blue screen, crashing in game. previously i had no problem just with 1 7800gt. is it because my pus, powerstream 520 sli, cant handle oc and 2 cards in sli? plz help, if so i will consider buying anohter one. btw i just had 2 hard disks and 1 dvd-rom device connected when running the rig. maybe the whole system is too hot with another 7800gt plugged in? my cpu temp fully loeaded is just about 50'. this morning i ran day of defeat source with the case opening one side panel and letting a fan blow next to the case. i didnt encounter any locks-up problem that i used to do. but i failed running 3dmark 03 that locks-up happened in 2nd sequence. as i tried lowering my cpu back to stock setting, 3dmark 03 ran successfully. so is it either psu or overclocking problem? and which psu do you guys suggest for my oc and 7800gt-in-sli rig? but seems people who have great quality psu, like nvidia certified, still have their games crashed and locked up when running either 1 or 2 7800gt in sli. i'm now very frustrated with my rig. sigh!!!!