Prime95
http://www.mersenne.org/freesoft.htm
Download:
http://mersenneforum.org/gimps/p95v259.zip
The i7 runs hot. When running the Prime95 Torture Test for the old Athlon XP, alarm bells went off when the temperatures zoomed past 60° Celcius but I understand realistic OC threshold is now raised toward 90° for max stress when it comes to the i7 CPU.
For my i7 920, Prime95 number of Torture Test threads should be 8 for the i7 CPU, not 4 like with the older CPUs.
The program should not give any errors.
It may be necessary to run the program 12-24 hours to make sure an overclocked system is stable (no program errors displayed).
If you get errors only after several hours, this is a result of slight instability because the system is running with little or no margin. It's stable enough to boot and to be moderately stressed, but as soon as the system is under enough load to go over that critical point, it may freeze. To be 100% stable, Prime95 should run 12-24 hours without any errors.
The point of testing is to see if you get errors or not thus testing the stability. The meaning of errors themselves is not as important.
I'm old school and use Prime95 but I'm sure there are others.
http://www.ozone3d.net/benchmarks/fur/
Furmark is an extremely intensive (overkill really) video card test. It gets cards so hot, I can't even pass it at default settings unless I have no cards installed immediately next to the video card, blocking air flow. Rename FurMark.exe to anything else since video card drivers may be programmed to not allow FurMark.exe to run full stress test if the exe file is named FurMark.exe. Lots of people think FurMark gets cards unrealistically hot...
To test memory only stability, use
http://www.memtest.org/
Memtest86+ cannot be executed under Windows.
It needs to be loaded from a floppy disk or USB or CD/DVD.
Note that after the boot media has been created you may not be able to read it from Windows. This is normal.
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Intel i7 920 [211] BCLK x 19 = 4.0 GHz @ [1.4500] CPU Voltage & [1.35000] QPI/DRAM Uncore Voltage, Batch 3836A394
3 x 1GB G.SKIL DDR3 1333 (PC3 10666) [DDR3-1691MHz] 10-10-10-24 @ 1.64 DRAM Bus Voltage
ASUS P6T Deluxe v.1 [LGA 1366 Intel X58] BIOS 1606
Thermalright Ultra-120 eXtreme 1366 RT with 120mm Scythe S-Flex F fan
ASUS EAH4850 TOP Radeon HD 4850 512MB @ 680 MHz GPU & 2100 MHz Memory
Antec nine hundred case, two front 120mm fans, one back 120mm Fan, one top 200mm fan
Corsair CMPSU-750TX 750W