Gigabyte 8600GT 256mb x8 vs x16?

[Platinumz]

I'm just wondering is there a big difference in performance if my card is running at x8 than x16?

CPU-Z Reports that my motherboard supports x16.

My card is running at x8 and I can't make it run at x16 on my motherboard.

Is it due to limitations on the card itself or the motherboard I'm running?

Specs:

M2N8-VMX Motherboard
Gigabyte 8600GT 256mb (overclocked Core Clock 650mhz, Memory Clock 928mhz)
AMD Athlon 64 X2 4000+ (overclocked 2.44Ghz)
Windows Vista Home premium 32bit
Sound Blaster Audigy Value

 

[xc0mmiex]

very very little, virtually negligible... 8600gt is not powerful enough to take advantage of the full x16