What kind of stop error? Does it pinpoint a specific file or particular type of stop error? Perhaps something like KERNEL_INPAGE_ERROR or something equally scary?
Blue screens usually pinpoint memory, disk, or memory/disk related errors.
Since you have formatted, this is apparently a system-wide hardware/configuration problem. We can deduce that the chances of this being soley a Windows problem is slim.
Try disable any Video/BIOS shadowing in your BIOS. If you have the option, disable "quick boot" in the BIOS so your PC will run a full memory test (if the memory is bad).
Check all of your fans, do a full format on your hard disk (not a quick format) and I recommend a a full disk sector test to make sure there are no bad sectors.
Check all cables and jumper settings. yada yada yada.. The usual troubleshooting stuff should not be overlooked.
I recommend getting that CMOS battery replaced, otherwise your computer can't hold configuration settings in the BIOS. I've never experienced what you are because of a missing/bad battery, but it will be good to factor this out so you can completely take this out of consideration.