Hi joncr, did you try running tests for the RAM or the Intel® Processor Diagnostic Tool?
Did you check the temperature in BIOS or swapping components?
Thanks for the reply. Sorry that I didn't list what we've tried so far but I thought that it would be implicit that I've tried pretty much everything before I posted the question. Here goes:
Intel Processor Diagnostic Tool: Yes, tried it. It passes with hyper-threading turned OFF, but fails with hyper-theading turned ON; it fails on the Stress Test part of the test; the machine LOCKS UP
Intel Extreme Tuning Utility: With hyper-threading turned OFF it passes a short stress test. It fails the stress test with hyper-threading turned ON immediately (LOCKS UP). Btw, I should add that I'm not using this utility to push or overclock this system; I'm just using the stress test.
RAM tests: Yes. I used Memtest and ran a fairly exhaustive test. In case you are not familiar with this app, it boots from a CD and bypasses the OS and tests the RAM directly. The system PASSED the RAM test.
Temperature: I've checked the temperature in the BIOS and using the Extreme Tuning Utility and it seems fine. I'm also using Core Temp to monitor temperature. The cooling system was upgraded about 14 months ago and it's pretty robust.
Passmark Performance Test: There are 9 tests in the CPU part of this test suite. With hyper-threading turned off, I can run 8 out of 9 tests. With one of the tests, the system LOCKS UP. That test is Encryption. This is the only example where something that I've tried has failed with hyper-threading turned OFF. With hyper-threading turned ON, I can run only 7 out of 9 without the system locking up. The 2 tests that cause a lockup with hyper-threading turned on are: 1) Encryption & 2) Sorting.
Various real world apps: doing CPU intensive activities (3ds Max/3d Rendering & Handbrake/video conversion) will work fine with hyper-threading turned OFF. They lock up / freeze almost immediately when hyper-threading is turned ON. Both of these apps are multi-threaded. So, apparently if an app uses multi-threading and it's available the system locks up.
Lastly, you mentioned 'swapping components'. Could you be a bit more specific? Is this along the lines of 'throwing a bunch of stuff at the wall' and seeing what sticks? :-) Or, is there some rational course of action that you are suggesting?
The CPU is a little over 3 years old; I doubt whether it is still under warranty, but I'll check. In a case like this, the other variable is the motherboard, and it could very well be the motherboard that is the problem not the CPU. Do you agree that this is also a possibility?
The board is an Intel DX580G and it was purchased in late 2011 at the same time the CPU was purchased. In any event if I was to swap one of the other I'd just need to make sure it was socket 1366 LGA. The shop that built the system for me is getting another board that is socket 1366 and the guy there suggested that I bring my system back to him so he can try the new board with the CPU and see how that goes. I may let him give it a try.
Btw, a friend has the exact same CPU / motherboard combination that I do and he's having the same issues.
Are you an Intel employee? Look, I appreciate your attempts at helping here but all the info that you have given me has added nothing to my level of knowledge of this problem. Your suggestions are along the lines of 'Capt. Obvious' from that hotel commercial that is on TV. It's obvious that in order to isolate the problem I need to swap these two components one by one and see which one is the problem. But that's easier said than done both financially and for time. I don't have spare CPUs and motherboards floating around and swapping out a motherboard to do a test is not a trivial matter. That's like downplaying how serious performing a heart transplant is. Btw, both of these components are Intel; both the CPU and motherboard. Were these even tested together by Intel? As I stated before, a friend who has the same CPU/motherboard combination is having the exact same symptoms with locking up.