AMD "Thuban" Core (Phenom II X6) XS Overclocking Charts

[Roman2K]

After a time consuming trial and error, I finally achieved 4 Ghz stable for a night:

• CPU Model: AMD Phenom II X6 1090T BE
• CPU Stepping: CCBBE CB 1022BPMW
• CPU Frequency: 4000 MHz
• CPU vCore: 1.425V (LLC off)
• CPU Multiplier: 20x
• CPU Turbo: Disabled
• CPU NB Speed: 2800 MHz
• HT Ref Speed: 200 MHz
• RAM Speed: DDR3-1333
• RAM Timings: 5-5-5-15-1T
• RAM Configuration: 4 GB (2 x 2 GB)
• RAM vDIMM: 1.5635V
• Motherboard: ASUS Crosshair III Formula
• Chipset/Socket: AM3, 790FX + SB750
• Cooling: Watercooling (Black Ice SR-1 560 with CPU, GPU and MB in the loop)
• Temps: 36°C Load (cores as reported by Core Temp, haven't checked the socket temperature yet)
• Operating System: Windows 7
• 32/64-Bit: 64
• Stable/Suicide/Untested: Stable

Stable = Tested stable for almost 9 hours of BOINC (Einstein@Home) with Prime95 Small FFT running the the background, picking up BOINC's leftovers.



With the exact same stress test, vCore one notch lower (1.4125V), it crashed (BOINC's processes stopped and some Prime95 workers stopped) in the middle of the night yesterday. At 1.425V, it has survived the whole night. We'll see tonight if it's still running, and I will take the opportunity to report the CPU socket temperature.

As much as I like this constant 4 GHz overclock, I would have preferred to take advantage of the Turbo CORE feature, at something like 3.8 .. 4.2 GHz but even at 3.7 .. 4.1 GHz, it was unstable on a single active core at 1.45V so I have little hope.

I'm beginning to wonder if the mysterious CPU VDDA setting could have an inpact on high multipliers? Isn't it like the CPU PLL on Intel? If I remember correctly, increasing it helped with 30+ multipliers, maybe it would be the case on Thubans with 20+ multipliers. Has anyone experimented with it?

Also, I tried to reach the golden 3000 MHz CPU-NB clock with several HT Ref. speeds, without success, but in a weird way. After increasing the CPU-NB voltage several times, I was able to have it stable for about 1 hour of Prime95 Blend, but 1 time out of 4, it wouldn't post after rebooting (on purpose), telling me the overclock has failed. So 3000 MHz prevents it from booting 1 time out of 4 but once in Windows, it appears to be stable!? I would have thought if it can pass this long of Prime95, posting should never be a problem. Is 3000 a limit for the Crosshair III Formula?