I'm done oc'ing the CPU for now. I'll work on the ram timings next.
Too many voltage variables, so I tried out the auto oc bios feature again and used what voltages it gave me, except for the CPU voltages which were, IMO, too high.
I also added a second
fan to the heatsink. It's RPMs, CFMs and design are close to the Cooler Master fan that came with the Hyper 212 Plus. Cooler Master specs it at 19dB-A. It's quiet but 19 dB-A it ain't. It did bring CPU temps down ~3C.
Here's a few that were Prime 95 (Small FFts) 12 hours stable, ambient temp 22C, same bios settings as prevoius post:
Core Speed: 3.8 Ghz, Base Clock: 190, Bios CPU voltage: 1.325V, CPUZ: 1.312V idle, 1.320V load, VTT: 1.234V, PLL: 1.903V, PCH: 1.10V, Temps: 32C idle, 58C load, Mem Freq: 761 Mhz, mem voltage: 1.50V
No one has said much about the PCH voltage, but if I set it to Auto it failed.
Core Speed: 3.9 Ghz, Base Clock: 195, Bios CPU voltage: 1.3625V, CPUZ: 1.352V idle, 1.360V load, VTT: 1.279V, PLL: 1.903V, PCH: 1.120V, Temps: 33C idle, 64C load, Mem Freq: 782 Mhz, mem voltage: 1.50V
Again, if I set PCH voltage to Auto it failed.
I tried for 4.0 Ghz but it looks like it's going to need 1.4V or more. I'm still reluctant to go this high until I see more on this from TH.
Core Speed: 4.0 Ghz, Base Clock: 200, Bios CPU voltage: 1.3875V, CPUZ: 1.376V idle, 1.384V load, VTT: 1.309V, PLL: 1.903V, PCH: 1.120V, Temps: 34C idle, 67C load, Mem Freq: 800 Mhz, mem voltage: 1.50V. Good temps but failed after ~ 1 hour.
So for now I'm staying at 3.8 Ghz.
10/21
Ok, one more tweak, maybe, and I'm done. At 3.8 Ghz I lowered the VTT to 1.204V, below Intel's recommended 1.21V max. It passed 12 hours Prime 95. If I set it to Auto I get a BSOD before it boots to Windows. I tried setting the PLL to 1.812V but it fails in about 30 minutes. I might try some more PLL voltages between 1.812V and 1.903V.
Asrock P55 Pro, bios V1.90, i5-750 3.80 Ghz @1.325V bios, Cooler Master Hyper 212 Plus (2 fans) with TIM Consultants T-C Grease 0098, G.Skill Ripjaws 4GB (2 x 2GB) DDR3 1600 @ 760 Mhz 9-9-9-24, 1.5V, OCZ ModXStream Pro 700, MSI NX8800GT, Win 7 Ultimate 64bit