MemTest86 v5.1.0 Freeze On Multicore Mode

[TechniMan]

Hi, hopefully someone here can help me:
My brand new PC (well, about a month and a half old now) has been freezing up at seemingly random times. Somtimes it might only be able to go 10 minutes before it freezes, other times it can go on for hours at a time without crashing at all whatsoever. So I was recommended MemTest86 by a friend at work, and have since run it on the PC (installed v5.1.0 UEFI on a USB drive). With default settings, it passed all 10 tests on 2 passes (having taken over 2.5 hours for that, I decided it was probably fine whilst also a little disappointed that I was yet to find the actual problem). But then I looked into the settings and noticed that I could run it with multiple cores instead of single, so hoping to get through multiple passes much more quickly. However, when I set it to parallel, the tests will stop during test 2 (by which I mean the program hadn't frozen, but the percentage wasn't moving after a few minutes when before it was quite fast). In parallel, it will also display W for cores 1 and 2 instead of the spinning | it shows for 0 and 3-7. And when I try Round Robin or Sequential it will freeze as soon as the test is about to start (the time isn't even displayed yet). I tried to test with Single Core using each core one at a time and the PC freezes again when trying to use any core besides 0.
Is this a bug in the program or could there be something wrong with my CPU? I hope this is enough info, if you need anything else I will do my best to get it.

My PC was built by PCSpecialist in the UK and here is the part list: http://uk.pcpartpicker.com/user/TechniMan/saved/sjBrxr
For quick reference, an AMD FX8350 8-core at 4.0GHz and Kingston 2x4GB at 1600MHz. BIOS is at default settings.
I have been in contact with them and they seem convinced tha tthe freezes are to do with Windows and are repeatedly telling me to reinstall, though trying that a few times has not yet yielded any success.

[David (PassMark)]

The CPU and GPU you have selected are both pretty power hungry. Around 125W + 150W. So this is already around 300W before the other components are considered. You probably haven't quite exceeded your 450W PSU, but would be getting close when the system in under load.

If it is a new machine the next thing to check is the CPU temperature while under load. Having poorly connected heat sinks is very common on new machines.

Then check to see if there is newer BIOS firmware for the motherboard.

We aren't aware of any bugs in MemTest86 V5.1. that would cause this.

[mig]

I agree, it has too little power. At my opinion you are short for branded 100W.

Cheers

[TechniMan]

The normal running temperatures are 40C for the CPU and 30C for the GPU. Trying heavy load now, Skyrim + a few graphical mods gives me 46C for CPU and 55C for GPU, though I have seen the GPU getting into the 60s for another game (can't remember which). It is able to keep very cool, and it can be running games like this for hours on end without any problems, but it might just freeze after half an hour. It's unpredictable.

The PCSpecialist site calculates the power requirement and recommends a slightly higher power PSU if you select a lower-end one. While I don't doubt you guys know your stuff, I just think that it would be very odd that they build the machine and go through testing it without raising with me any concerns they have over power consumption. If you really think power is the problem, they do offer an upgrade service, but it would be annoying to have to buy a new PSU and have them fit it and such, especially if it turns out to not be the actual problem.

In terms of BIOS, I have now checked and it seems to be that I am two versions behind (current from 21st Nov '13 and latest released 14th May '14) and missing some stability improvements. So I will upgrade this and if I manage a week without any freezing, then it must be that was the cause.

Thank you very much for your help!
- Will

[David (PassMark)]

Yes, try the new BIOS and see how that goes.

PSU calculations can be tricky as in theory you need to do the calculation for each voltage level (5V, 12V, etc..). But as this is normally too much hassle to do, plus the information isn't always available for each component at each voltage level, people tend to over dimension the PSU a bit. It also allows for future upgrades. 450W is probably OK

[TechniMan]

OK, new BIOS didn't seem to change anything. Over the Saturday & Sunday, it still crashed a lot, even when it wasn't particularly busy (maybe just a YouTube video and little else). However, on Sunday evening, it was not able to boot properly anymore. I'm currently going through this new problem with the manufacturer and hopefully we'll get that and eventually the crashing all fixed up.
Again, thanks for your help, updating the BIOS is totally a great this in the long run but unfortunately not in this case. I have also told them that it's been brought to my attention that the PSU is potentially not good enough, but like you they think until we rule other things out it's probably fine.

Cheers David,
-Will

[David (PassMark)]

The failure is probably a good thing.

As long as you have a backup of your data a total failure of the machine during the warranty period is preferable to have some intermittent and nebulous problem that drags on forever unresolved. Vendor can't deny there is a problem if it doesn't boot.

Worst case however is that the boot problem has been caused by data corruption on the hard drive which in turn has been caused by the repeated lockups of the machine in Windows. A reinstall of Windows might fix the corruption, but not the underlying issue.
I guess you'll find out soon enough.