Windows SMP and Dell/Windows SpeedStep: Weird Problem Fixed

Leonardo

My laptop, Dell Inspirion E1405 (C2D T2400, 1.83GHz) was folding very slowly with SMP - 50 minutes/frame on a 2651. Now I realize a T2400 is not rocket, but still, 50 minutes? I checked the CPU speed with CPU Z and it showed 980MHz. I checked CPU performance with Windows Task Manager and it showed full engagement with both cores. Hmm, just didn't seem right, as frame times on a 2651 were 50 minutes. OK, it's not a high performance machine, but it's not exactly an old P4 or Athlon XP either!

Previously, I had turned off SpeedStep in the BIOS thinking that would prevent the CPU from throttling. I was wrong. Just the oppositie. Turns out that SpeedStep was throttling the CPU at 50% core speed. With SpeedStep turned off, the CPU would not go faster than 890MHz, regardless of the load on the computer. I turned SpeedStep back on and voila, the computer is folding at 1.83GHz, exactly where it should be.

profdlp

Good old computer logic; you have to turn it on to make it stop.

Leonardo

Good old computer logic; you have to turn it on to make it stop.

Wouldn't have believed had I not seen it. I tried everything I could think of to get the processing running at full speed. Tested this, tested that, monitored this, monitored that. Nothing worked. I searched high and low on the Internet, and all I got concerning the Inspiron BIOS was pablum directed at low knowledge level off-the-shelf buyers! I now feel quite vindicated for not having purchased an branded computer in ten years, until this one. But then, one doesn't exactly have much choice when it comes to laptops.

That was unkind of me. There's nothing wrong with someone wanting off the shelf. After all, that's the way we buy toasters, microwave ovens, and clothes dryers. I should have said "directed at non-hardware oriented" computer users.