Overclocking E6600 and XFX GeForce 9800GTX Sli...poor results!?!

Hey guys,

I had a bit of free time over the weekend and decided to dust off my old desktop and give it back a bit of juice. Here are the Specs.

Asus P5N32 sli SE deluxe
Intel E6600 @ 2.67Ghz stock speed
2x XFX Geforce 9800GTX in SLI

using a ZALMAN 9500A cpu cooler and stock cooling for the GFX cards

Now I know this MB is pretty bad for overclocking but I still gave it a shot. Stopped at 3Ghz 1200Mhz FSB for now as it is stable and wanted to try and OC the GFX cards a bit.

Before doing so, I ran 3D mark 2006 with the OCed processor and the stock GFX cards and got around 14000 which is an okay result for such a configuration.

However, after I proceeded to OC the graphic cards, 675 -> 775 core speed and 1100 -> 1200 memory speed, my 3D mark 2006 dropped a good 1500 points which got me puzzled. My CPU score stayed the same but both graphic scored went down.

Would anyone have any idea as to why I actually got a performance drop?

I know 3D mark 2006 is not the most stable benchmarking tool but still, I would have at least expected a slight increase.

Thanks for your responses

PS: I'm using windows 7 RC with the latest forceware drivers