Couple of days ago apps on my computer started shutting down by itself and the OS started reporting random missing files. I thought that my SSD was failing, but it passed integrity, performance and error checks. Soon after I started getting BSODs.

Next I tested the RAM modules. One by one in multiple motherboard slots.

All 6 RAM modules fail at the memtest86 test #4 on the third or the fourth pass (image attached at the bottom). I tested the memory on another machine and tests couldn't find any problems with the memory modules. I took Crucial Ballistix Sport 1 x 8GB from another machine and it fails at the same test.

I don't know what to made of all this. I'm down to CPU and Motherboard. Could it be the CPU or corrupted BIOS? What tests can I perform to make sure the CPU is not failing?

Memtest86 Test 3 [Moving inversions, ones&zeros, Sequential] - This test uses the moving inversions algorithm with patterns of all ones and zeros. Cache is enabled even though it interferes to some degree with the test algorithm. With cache enabled this test does not take long and should quickly find all "hard" errors and some more subtle errors. This test is only a quick check. This test is done sequentially with each available CPU.

Test 4 [Moving inversions, ones&zeros, Parallel] - Same as test 3 but the testing is done in parallel using all CPUs.

I'm running:

  • P6T7 WS SuperComputer Motherboard
  • Intel Xeon W3690 CPU (6 cores, 12 threads)
  • 6 x 2GB Corsair Dominator DDR3 1600 (PC3 12800), Timing 9-9-9-24, Voltage 1.3V-1.5V (X.M.P.)

Memtest86 Error #4

  • If you have tested the memory in another system, then it is safe to say, the memory isn't the problem.
    – Ramhound
    Commented Jul 20, 2016 at 15:33
  • That is my assumption as well. I just wanted to hear more opinions on the subject, before I start spending on the wrong item. Memtest test number 4 is done in parallel using all CPUs. I wonder, if the issue is in the CPU.
    – GTodorov
    Commented Jul 20, 2016 at 15:35
  • A Q&A site like Superuser really isn't the place to gather opionions though. If you want opionions there is our chatroom for that purpose.
    – Ramhound
    Commented Jul 20, 2016 at 15:37
  • 1
    I'd start with the motherboard. it is the more likely of the two to experience failures over time. Commented Jul 20, 2016 at 15:38
  • @FrankThomas thanks Frank, I will test the motherboard once I get home later today. I think I can find a working CPU to test with.
    – GTodorov
    Commented Jul 20, 2016 at 15:40

1 Answer 1


Easiest way would be to test the CPU in another known-good system. If it passes, then the issue is likely your motherboard.

Be sure to check other candidates if you haven't yet. Swap power supplies if you can, and also look for leaking or damaged capacitors on the motherboard. Poor power makes your computer unhappy.

  • I changed power supply within the last 6 months. Running EVGA P2 1600W. I don't have another motherboard, but I think I can find a working CPU.
    – GTodorov
    Commented Jul 20, 2016 at 15:42
  • @GTodorov still a good idea to check it. I had a new 600W PSU that did really weird things (like shutting down my PC at a certain point in Deux Ex: Human Revolutions, but being able to get past that point if I rebooted). But I agree that it's more likely to be something else (i.e., motherboard) Commented Jul 20, 2016 at 15:43
  • I have another power supply, I will not ignore your suggestion and test the PSU as well. I'm leaning towards the motherboard though. Hopefully it's not the PSU.
    – GTodorov
    Commented Jul 20, 2016 at 15:54
  • 1
    I did some cleaning to the RAM lanes with CRC electric cleaner, cleaned the modules and the CPU. I switched the xeon W3690 CPU with working i7-920, and DDR3 Crucial Ballistix Sport 1 x 8 GB. But the memory test returned errors again, so it's not the CPU and it's not the RAM. So I downgraded the BIOS to the official ASUS v1001 from FOONUS MOD BIOS v1102. Memtest86 is running for almost 15 hours now with no errors, I will let it run for another 9 hours so it passes the 24 hours period and I will install the Xeon W3960 CPU and do another Memtest.
    – GTodorov
    Commented Jul 21, 2016 at 15:26
  • @GTodorov wow, wouldn't have suspected the BIOS! Might want to make a note of that for future readers. Commented Jul 21, 2016 at 15:27

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