Working as a contractor at an unnamed company, I doing most of my daily work at a HP NC4400 notebook. A fine machine, sporting a Dual Core processor in a nice, small package.
Ever since I use the notebook, I've been somewhat distracted by the constant fan noise and high temperature. The fact that the machine would only give me 1 hour runtime on battery (after some conditioning, albeit a Li-ion battery) gave me the idea something was keeping the processor busy.
The machine is running a *ahem* locked down Windows 2000 installation and I could not find any noticeable processes causing high CPU load. I had the machine inspected (seems the heatsink is sometimes not properly attached to the CPU) and re-imaged subsequently. But no luck. So I've tried not to be bothered too much and got myself an extra battery (2/5 hour runtime with both batteries, grrr..)
Until today, when I found someone on a forum stating the Speedstep functionality doesn't function well on Windows 2000 if Dual Core is enabled in the BIOS. Similar things on HP's forum. Although Speedstep seems disabled (and greyed out) in the configuration panel. it works. With the extra battery I had the machine running for 3 hours with 50% battery power left. I must admit that the next 50% only lasted 1.5 hours, as this was the standard battery with less capacity, but still, a 100% increase in battery life. The cost of course is the loss of the second core, but I haven't yet noticed that much of a difference, running Outlook, Internet Explorer and the like.
So a quick tip for people running Windows 2000 on a recent notebook: if your machine gives you bad runtimes (and is getting hotter than expected), try disabling the dual core functionality in the BIOS. Ofcourse I'd say don't run Windows 2000 on modern hardware, but if you insists, try doing so in a virtual machine. If this means you keep your dual core functionality, there probably isn't a performance penalty at all.