8x agp problem

ok everytime i put my settings on 8x agp in the display properties my computer will randomly restart or just give me a black screen and i have to restart it manualy. it does it when im playing games or on the web or when im on aim.
heres my specs

Amd 64 +3500
Xp profesional w/ sp2
Ultra pc 3200 (1 gig) ( 2 x 512)
Maxtor 100gig hard drive
Asus A8V Deluxe
Radeon 9600xt 128mb
(its not my psu either cause i just replaced that with a new 550w one)

i have tried everything i can think of..please help

 

keep it in 4x? its not like a 9600 requires 8x agp bandwidth

 

ya i know it doesnt require it...i just dont like the fact that it has the ability to be on 8x but fails at being stable at 8x. :\

 

could be a faulty bios, bad drivers for your mobo, etc...

 

oh..the joys of having built my own computer....ugh