Dell :: 93006800 Ultra Throttling

My Inspiron 9300 has the following specs:

Pentium M 1.6Ghz pin modded to 2.13Ghz (previous CPu was 1.73Ghz) , 2Gb RAM (667Mhz sticks), 6800 Ultra (Xps Gen 2 Bios flash-A05, previous card was an X300 64MB.)

I seem to be getting odd 3DMark05 socres, around the range of 4500, I tried overclocking the 6800 Ultra to 500/1166 and that produced a result of around 5000. The odd thing is that 3DMark05 appears to be running "choppy" every other frame it seems to skip producing a choppy flow of the tests, the frame rate also fluctuate by about 5 FPS in somewhat low movement/action scenes.

I have tried numerous drivers all resulting in the same thing (every driver has been cleanly installed). I am also quite certain that it's not a temperature issue as the max temp the card reaches (according to I8kfanGUI) is around 80-85 C. Just to be certain I ran 3dmark while the laptop was in an ambient temp of -5C (holding laptop outside the window ;]) and still the same...although max temperatures were a lot lower.

So is it possible that the card is for some reason throttling back and forth from the high performance 3d profile (450/1064/1.38v) to the low profile one (250/658/1.1v)?

I got the card from eBay over a year ago now and thus have no warranty on it.

Has anyone else had a similar problem and found a solution?

I am currently considering flashing the card with a custom BIOS, using NiBiTor 3.6 get BIOS from card, change ONLY throttling values to 450/1064 and also voltage to 1.38v, do not touch anything else, save the BIOS burn to CD (alongside a copy of original BIOS read from card)-[no floppy] and flash.

However I am a bit worried about killing the card, has anyone attempted something like this? Also the ROM files generated by NiBiTor are exactly 64,000 bytes is this alright?