Are factory OC'ed cards reliable?  
 
I have 2 that broke in a row 1st a ASUS 7900GT Top and now a MSI 8800GTS 640MB OC. Error message in Vista: "display driver has stopped responding and has recovered" (in game blank screen / no signal on LCD / CRT seems to degauss) and in XP the PC freezes and blue-screens.  
 
I am curious, how many of these factory OC'ed cards  

It may be an issue with cards from ASUS or MSI as I have had factory OC'd cards from both BFG and EVGA and did not experience any issues with either. Actually, I was able to further OC each of the cards. I  currently have an EVGA 7900GT CO Superclocked (OC'd at factory to 550/1580 and then to my OC of 575/1600) for about two years now with no problems at all.
 
I highly recommend EVGA products and will probably continue to buy them exclusively unless HIS comes out with something really tasty from ATI/AMD.
 
Are you sure it's not a Vista? Or driver issue?

I voted no... but my 7800 GTX only had a 15 MHz (seriously) OC over stock. Thanks XFX!

Yea, it sounds more like a vista problem to me. I know vista is completly incompatible with my 7900GT and somewhat works ok with my 8800GTS  
Id try XP before giving up. Vista is satan when it comes to video cards.
GL

I think it all really depends on the GPU you're using. I had two bad HIS ICEQ3 Turbo X1950 Pro AGP cards that came overclocked using a 620 Mhz. Core / 1480 Mhz memory effective. The X1950 Pro GPU in general does not overclock well and HIS found this out the hard way. They later re-issued the X1950 Pro as a Rev.2 (V2) and down-graded the core clock to 590 Mhz. and upped the memory to 1540 Mhz. effective using  1.2 ns VRAM.

I don't believe it is vista, i have been playing bioshock for days with no problems. Havent changed any drivers between working and busted card. Also, it's not heat related.

My BFG OC2 works great!

For me no
XFX 8600GT XXX
out of the box:620/1600mhz
stock:540/1400mhz