Problem with Hard Freezes on New Lynnfield Build

Hello all. Thanks in advance for taking a look at my problem and sharing your thoughts.

I recently built a new system with the following components:

Intel Core i7 860 CPU 2.8GHz
ASUS P7P55D PRO LGA 1156 Intel P55 ATX Intel Motherboard
G.SKILL 8GB (4 x 2GB) low voltage 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666)
Thermaltake Purepower W0100RU 500W ATX 12V 2.0 Power Supply

I reused a couple of SATA HDDs and an IDE DVD-RW drive. All of this is housed in a very well-ventilated Thermaltake V9 case.

I have been running Windows 7 32-bit RC and switched to Windows 7 64-bit this week.

I started with all BIOS settings at the defaults / auto settings initially, except for RAM timing, which I had to set manually. The PC would crash frequently after being on for about an hour or two, going to a BSOD with the message “a clock interrupt was not received on a secondary processor.” Sometimes it would just lock up, with the action on screen hard freezing unless I reset the computer.

I tested all RAM in another PC and via DOS-based Memtest86. All passed with flying colors.

I then read on some overclocking site the “clock interrupt” error, at least for a Lynnfield processor, could be due to insufficient Vcore, or CPU voltage.

For Lynnfield, the max is apparently 1.40V, so I upped my Vcore in that direction, which seemed to stop the “clock interrupt” error. I was still getting hard freezes after an hour or two, so I did some additional research. I found some posts online that suggested raising what Asus calls “IMC voltage,” or integrated memory controller voltage. This is apparently what they call the DRAM controller that is now integrated into the Lynnfield chip. I upped that gradually to 1.35V but am still getting hard freezes.

I am really getting frustrated with this process and hope that someone else has experienced this problem and has some ideas. The PC passes OCCT, Linpack, and Prime95 just fine, but simply leaving it on, running Media Player or a web browser seems to be enough to result in a hard freeze.

All ideas for getting the system stable are appreciated! Not looking to overclock, just to stop the freezes.

I should add that I have a decent aftermarket CPU cooler and idle temps are about 31C, spiking to 70C on Linpak, so I don't think that this is a thermal issue.

David