PSU: OCZ ModXStream Pro 700W Modular High Performance Power Supply
CPU: AMD Phenom II X2 555 Black Edition Callisto 3.2GHz Socket AM3 80W Dual-Core Desktop Processor - C3 Revision HDZ555WFGMBOX
CPU Cooler: Corsair CAFA50 A50 Air Series Performance CPU Cooler
MB: ASUS M4A88TD-V EVO/USB3 AM3 AMD 880G SATA 6Gb/s USB 3.0 HDMI ATX AMD Motherboard- BIOS V.2201 (05/11/12)
RAM: 4x Kingston HyperX Blu 2GB 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model KHX1600C9D3B1K2/4GX AND/OR 2x G.SKILL Ripjaws Series 4GB 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666) Desktop Memory Model F3-10666CL9D-8GBRL -in various combinations, with no effect on the problem. Most testing was done with the 4 Kingston sticks. Currently running the two G.Skils and two of the Kingstons, to maximize what I have on hand.
Boot Drive: Kingston 64GB SSDNow V100 Series 2.5" SATA II
Storage: 2x SAMSUNG EcoGreen F2 HD154UI 1.5TB SATA 3.0Gb/s 3.5" AND 2x Hitachi GST Deskstar 5K3000 HDS5C3020ALA632 (0F12117) 2TB 32MB Cache SATA 6.0Gb/s 3.5"
The only problem I have is that when I unlock cores, it will sometimes restart during the Windows logo screen. No BSOD, and never fails to post. The problem is intermittent- the only way that I've found to test for it is to change a setting in the BIOS, and then boot into Windows and restart over and over until it manifests. Unfortunately, it doesn't take very many times (~<5). This problem occurs when I unlock the cores manually one at a time, or leave the bios setting on Auto. I have raised the CPU voltage as high as 1.45 (default is 1.4), which from what I've read in other threads, should've been sufficient if that was the problem. In an effort to get "safe" voltage increases that might solve the problem as a side-effect, I also tried the CPU Overclocking Overclock Profiles for 2%, 5%, and 8%, and ran the OC Tuner Utility, which seemed to settle on 8% also.
Here's the sticky part, and what seems to set this apart from all of the threads on this topic that I could find. After each of the changes in the BIOS, I ran Prime 95 blended for no less than 4 hours, and overnight in some cases. None of the cores ever had a single failure or error. After each test, I booted back into the BIOS and checked the temps- they were never above 45C.
I would be happy to live with this minor problem, since it seems fine as long as it boots into Windows, but I'll be connecting remotely to this box quite often, and leaving it unattended for weeks in the mean times. If I can't trust it to restart successfully with 4 cores, I'll have to leave it locked.