Do u really see a fall in the FPS of games???
Use FRAPS to check this out at
http://www.fraps.com
Expertool functions fully only if u use GAINWARD drivers.
If u don't see any fall then it should be a error in dispalying memory.
why don't u use POWERSTRIP to OC
http://www.entech.com (hopefully)
Tell me one thing when u boot ur PC what does the Video BIOS, the one that flashes before ur PC BIOS show. I mean what memory size it shows. if its original size then its OK or if it also shows 8mb sorry to say ur rest ramchips may b corrupt. although i hav never heard this. so don't b nervous. if everything ok there then u "ll hav to do the following
take ur GFX card to ur friend's PC. he shud hav a mobo with AGP slot. plug it there and install the drivers and tell what it shows in nvidia control panel. if u see 8 mb there, take the card to dealer, if u see original size remain cool. it's a problem of wrongly installed driver. Use driver cleaner to completely remove nVidia driver. and try installing the older one.