E6400 Overclocking with DS3 - Graphics Stutter

Hi,

I've been overclocking my e6400 system on the Gig. DS3 and am having a few problems with my graphics card stuttering after overclocking.

System spec: e6400, Ds3 (F5), Corsair XMS2 6400 4-4-4-12 1gb, Mem. multiplier 2.0, 7900GT Gainward, 256mb locked at 100mhz (tried auto also) in the BIOS.

It doesn't really matter what speed I overclock to, 2.5ghz or 2.8 (my maximum) all show the same problem with my graphics card. The pictures jumps even few seconds and basically isn't very smootth at all. However my system is stable, at about 46 temperaure. Note, the graphics are perfectly smooth at normal FSB speed. (not overclocked). So the issue must be to do with the overclocking of the FSB.

I set the PCIe frequency to 100mhz from the default of auto - which I thought would be locking it but it doesn't seem to be hence the jerky graphics. Is there something else I have to do to lock it?

I'm using EasyTune 5 to acutally overclock.

Note, I've NOT done any overclocking on my g-card, only the CPU/mboard. Also I've read, re-read and read again wusy's guide to see what I'm doing wrong! No luck yet!

Any help/pointers would be appreciated as it seems a waste to have a stable system but unusable because of the unsmooth graphics.

Thanks in advance,
Dominia