I7 overclock slows graphics card

[bokan]

So I have noticed that whenever I overclock my i7 920, my graphics performance goes down. Does this have anything to do with the PCI bus voltage? Does this even make sense? (if it helps, I have been having trouble getting the chip to boot over 3.3 GHZ or so, even though I have great airflow and a bunch of aftermarket cooling stuff)

 

[bokan]

I was hoping for some sort of a universal phenomena, but I suppose it's not that common.

Specs:

core i7 920
asus p6t
6gb kingston hyperx ddr2000
nvidia gtx 295
950 watt psu

Even with low overclocks (just the XMP ram setting with a bit higher BLCK) it seems like I'm seeing an effect.

It's like the graphics card is skipping, almost.