X2 550 BE C2 - Attaining 4GHz?
 

My C2 revision Phenom II X2 550 Black Edition will do (200x19=)3.8GHz stable at 1.5v with temps under 40c. I can POST and occasionally boot at 3.9GHz, but it usually isn't stable for long. I've tried bumping core voltage up to 1.6v with absolutely zero improvement in stability (temps reach ~55c). I've bumped miscellaneous voltages to try to improve stability, but it seems that nothing helps.

I know 3.8GHz is about where I should be at on an older C2 stepping, but can anyone explain what's stopping me from going any higher? (..and/or tell me what's safe as far as voltages go?)

Hardware at a glance:
Phenom II X2 550 Black Edition
DFI LanParty DK 790FXB-M3H5 (SB750) (10/9/2009 BIOS, latest)
Xigmatek S1283, OCz Freeze, Scythe Ultra Kaze 3000
<-- Check sig for the rest

Current BIOS settings:
CPU Core Voltage - 1.53v
DRAM Voltage - 1.8v
SB PLL - 1.2v (tried 1.3)
NB Core Voltage - 1.2v (tried 1.35)
NB PCIE Voltage - 1.12v (haven't bumped)
NB HT Voltage 1.27v (tried 1.4v)
CPU-NB Voltage - 1.25v (tried 1.4v)

CPU NB Clock Ratio - x13 (will not do x14 for anything)
HT Link Frequency - 2.6GHz (2.6 seems to be the max)
CPU Host/HTT Clock - 200MHz
CPU Host/HTT Adjust Gap - 5MHz
PCIE Clock - 100MHZ

My PhenomII x4 C2 wont go over 3.850Ghz @ 1.550v stable no matter what i do , so i keep it at 3.836Ghz with 1.525v

I doubt you can get much more... did you try unlocking to an 4 core?

I've tried everything except underclocking. No 4 cores for me. :(

Been there twice Sempron 140 & PIIx2 560 didn't unlock , it's sucks!...:mad:

The Sempron unlocked & booted as a dual core but froze at Bios post no matter what i've tried...
Anyhow i exchange it for a real dual core the AIIX2 240 & later on move to my PIIx4 now waiting for bulldozer or go for a PIIx6 , it will all depend on performance & the price tag...;)

As for the PII x2 560 (C3) it overclock pretty good got 4.1Ghz stable @ 1.450v , it was for a friend of mine & he is quite happy with it , in games there is no real difference between his dual core & my quad core (1-2fp/s max) but in benchmarks i am kicking ass all over his dual core...:D:laugh:

My girlfriend has, I think, an i7 920 (stock) and it kicks my butt as far as file compression/decompression goes.