I'm still working to get it fully stable before reporting final temps. Prime95 is going for about 10 minutes before cores start to throw errors ... only one is capable of continuing past that.
Temperature in my apt. is 22C and the motherboard is still reporting 30C. This cooler rocks.
I should note that I am close to finding a stable configuration, it is far
from stock and currently temps are running in the high 60s at 4Ghz. Among other tweaks, I've pushed the CPU voltage to 1.4v, which Asus claims is the minimum necessary to run a 200 BCLK.
Update: using the following settings, I was able to hold 4.0Ghz with a 200BCLK for 2 hours using Prime95 ... with a temp that maxed out at 72C. This is really close to my max, so I'm not excited about that .. but I'm smarter than the average bear.
CPU Diff Amp +900mV
CPU Voltage: 1.40v
Integrate Memory Controller Voltage: 1.38125V
I'm not happy with that temp but it is true that these boards really do need extra juice for 200BCLK. Thankfully, there is an alternative. Although the i5 750 is supposed to be locked with a 20x multiplier, the fact that it has the Turbo feature means that it isn't really
locked. Many enthusiast motherboards give access to the 21 and 22 multipliers used by the Turbo. Mine allows access to the 21. So I'm dialing down the BCLK and up the multiplier to see if I can get a better overclock.
I'm now trying to find stable and cooler settings at 4.0GHz using 21x190. Stay tuned ..