BIOS error with C1E/Speedstep function

Hi,

I wasn't sure how to put it into the subject but this is my problem, I own a xps 400/dimension 9150 with a 0FJ030 mother board BIOS revision A07. I recently had a new PSU configured to work only for a dell computer (460W as opposed to 375W which is what dell gave me initial so now there is plenty of power). I have an Intel pentium D 945 3.4ghz that is being underclocked by C1E/speedstep to 2.4ghz but shoots back up to 3.4 when I play games for example. It seems that the multiplier is not locked (17x200mhz regular to 12x200 underclocked) although I don't think that is the case. I have C1E/speedstep turned off but for some reason it want's to just sit at 2.4ghz
P.S. I don't have UPS enabled either if that helps at all diagnosing the problem