Hello all;

I am having a problem OC'ing my system I am hoping you can help with. I have the A8N32-SLI Deluxe, an X2 4400, 2x1GB of the Corsair 3500 LL PRO, an ATI All-In-Wonder x1800XL, Creative X-Fi music sound card, and a Silverstone Zeus 600 W PSU. Cooling is a Zalman 9500, My system runs Prime95 stable at default settings. I am using BIOS 1103.

I decided a good place to start was Cisco's guide, which suggests an initial OC of FSB 250, Multiplier x10, K8>NB 4x, Memclock 166, Memory Command rate 1T, all other memory settings auto, Cool 'n' Quiet disabled, PEG link disabled, SB>NB freq 200, SB>NB multiplier 5x, K8>NB and SB>NB linkwidth both 16x/16x, PCIe freq 100, all overvolts off, and the VCore at 1.35.

At these settings, the machine boots, and core 1 runs Prime95 stable for hours with CPU temps of 47-48. The problem is that I can't get core 0 stable at all. I have boosted the Vcore in increments to 1.435. Core 1 runs Prime95 stable for at least 6 hours, but Core 0 fails within seconds if I am testing both cores simultaneously (sp?). Interestingly, I ran Core 0 by itself, and it failed Prime95 after 2 hours. One observation...when I made the last adjustment in Vcore (from 1.4275 > 1.435), the Vcore as reported by AI booster and CPU-Z actually seemed to go DOWN. I was getting a reading of 1.42 from both. Also, my VCore seems to fluctuate a bit (according to CPU-Z) from 1.408 to 1.424 from moment to moment.

Here is my thinking. I am new to this, so bear with me if I say something stupid. Since Core 1 seems stable, the problems with core 0 cannot be attributed to any of the memory or bus settings. My initial impression was that Core 0 just needed a bit more VCore to function than Core 1, and it does run longer before failing with a higher VCore. I cannot fathom why Core 0 fails within seconds while I am testing both cores, but runs for 2 hours if I test it alone, unless there is a problem with power to the CPU.

Am I right in suspecting that either my PSU or the MB is bad? My understanding of these things is limited, but I do know that the MB takes care of distributing power to the CPU, right? My PSU should be more than adequate for my system, as far as I know. Or I just have a bad CPU for overclocking? Probably the best thing I could do as far as isolating the problem is to drop my CPU into a different MB and see if it works at 250 x 10, but I don't have one available.

Any help you guys could provide would be greatly appreciated.

Mark