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Are all of the power leads properly connected -- especially the 8-pin CPU power? I assume that you properly mounted the H100 and it's properly wired to to both the CPU_FAN header and the 4-pin Molex to the PSU.
If that's not the issue then Clear CMOS (don't forget to unplug the PSU ~5 minutes); see - http://www.youtube.com/watch?v=rdHH9KrceR0
Hi, thanks for the reply.
Just realised, i hadnt connected the 8 pin. thanks so much, silly me thought all motherboard and cpu were powered with 24 pin.