I'd been having troubles with my overclock ever since I got the 920 (idle at 55C, peak 90C at 4.0GHz), just put it down to an unlucky chip and didn't go quite so extravagent on the clocks.
Spent the day cleaning house and something has fixed it:
Took the motherboard out, so I could go through the rigmarole of getting the filter out of the 180mm intake near the CPU area to clean it.
Wiggled the H50 backplate around, when I put the pump / plate back in it seemed much harder to get it locked into place (much less clearance) - it wasn't loose before but definately isn't now.
Replaced a pair of Sycthe Kama PWM with a pair of Akasa Vipers.
One or more of those things certainly helped, dropping idle to 38C and load to 54C (on uncured AS5). So now to get it overclocked some more
It bluescreened after a bit on 1.3V CPU / 1.2V QPI at 4.0 - I assume that's the QPI needing boosting? (I had been running it at 3.7 with 1.2V CPU / 1.12V QPI)
(I nearly bought a H70, but cancelled at last minute as wanted to see what the fans would do)
Spent the day cleaning house and something has fixed it:
Took the motherboard out, so I could go through the rigmarole of getting the filter out of the 180mm intake near the CPU area to clean it.
Wiggled the H50 backplate around, when I put the pump / plate back in it seemed much harder to get it locked into place (much less clearance) - it wasn't loose before but definately isn't now.
Replaced a pair of Sycthe Kama PWM with a pair of Akasa Vipers.
One or more of those things certainly helped, dropping idle to 38C and load to 54C (on uncured AS5). So now to get it overclocked some more

It bluescreened after a bit on 1.3V CPU / 1.2V QPI at 4.0 - I assume that's the QPI needing boosting? (I had been running it at 3.7 with 1.2V CPU / 1.12V QPI)
(I nearly bought a H70, but cancelled at last minute as wanted to see what the fans would do)