Any way to disable the CPU slowing down to save power on Latitude D800?

I have a 2003 Dell Latitude D800 with a Pentium M 1.6ghz, when it's full speed everything is nice but it seems to slow down to 591mhz way too often, even when I'm clearly using the processing power. I never use the battery, so power saving doesn't mean anything to me.

Is there any way to disable this "feature" and just have the CPU running at full speed all the time? I imagine it would be a bios setting? I don't know how to access the bios on this PC, though.

Thanks.

EDIT: I have whichever the most recent BIOS is. A12 or A13, can't remember which.

 

Use RMCLock and disable everything but your highest multiplier. Though honestly, you should not need to do this. If the processor isn't running at full speed, you are either not stressing it enough for it to clock up, or your Speedstep is malfunctioning.

 

It's probably malfunctioning. It's almost six years old, remember.

I've also considered it may be due to high temperatures.