The system in my signature has both, W7 and W8 installed. The dual boot is managed by the EUFI/BIOS via the "F12" key, instead of using Windows for this purpose. As such, both OSs run on the same hardware; the only exception is the system or "C" drive, each OS has it's own SSD drive.

Despite the same hardware that obviously have the cooling capacity, there's a temperature difference between the two OS. This has been verified by HWMonitor:

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It's a sort of mixed bag, in W7 the CPU runs cooler while in W8.1 the GPU runs cooler. The latter one is probably due to utilizing AMD Eyefinity, or offloading the multi-monitor setup to the GPU.

In either case, W8.1 seems more power hungrary than W7. Did others noticed the same?