If you look at the Everest's FAQ, it says that Dell computers uses a different sensor chip and it is not supported by Everest. I also have a GX240 and haven't found a Temperature Monitor. In the Dell official site, there is a "Dell Diagnostic software" or something like that (you can find it in support>drivers and downloads), but I didn't try it (it needs floppy drives to install and I had none :P), so if you try it, or if you find a...