Fault in my new build machine - need some help!

[benc85]

Morning all,

So I have moved up a chipset to coincide with downsizing to m-atx and in doing so bought the following components to go into my SG10B:

Gigabyte GA-Z97MX-Gaming 5 m-atx motherboard
Haswell i5 4670K 3.4Ghz
G.Skill 8GB (2x4GB) DDR3 2400MHz TridentX Memory
Samsung EVO 840 250GB (Basic) Sata 3 SSD
WD Caviar Blue 1TB Sata 3 HDD

I also plonked in a couple of my existing components:
Pallit Geforce 570 GTX
Samsung Evo 830 60GB SSD
Coolermaster Silent Pro 600W Modular PSU

I also purchased a copy of Windows 8.1 OEM 64-bit to run it.

I'll mention everything that I've done as it might have some significance or part, however small!
So installation when smoothly, set the SATA controller to AHCI, no overclocks, windows installed without any issues or hiccups. Subsequently I've installed a few staple bits of software (steam, origin, ccleaner), chipset and hardware drivers and also had a go with the gigabyte utility software.
I then updated the motherboard BIOS from the F2 to F4 revision. After that I had a play with the settings using the BIOS (I enabled fast boot) and gigabytes' own OC windows utility. Picked their "moderate" overclock which was 4.2Ghz, rebooted, ran fine into windows. Picked the 2nd X.M.P profile for my RAM, ran fine, then tightened the command rate to 1T, again ran fine, ran a game for a couple of hours no issues.

I noticed the problem after leaving windows idle for a few hours. I'd come back and the mouse would respond, but no ability to interact with the icons in the taskbar, extremely slow, couldn't even draw selection squares on the desktop without heavy lag, took an age to CTRL+ALT+DEL, wouldn't run the start menu. In the end I had to do a hard reset.

So this is where I get concerned and decide to run Prime95. Immediately, the computer restarts when I initiated the test. So first thing I do is remove the overclock. Back into windows, the non-responsive behaviour persists on reboot this time - very odd. So I lax the memory to 2T. System seems fine. I started Prime95 last night and it ran overnight for 3/4 cores. 1 of the cores failed after 1hr29mins as it "rounded to 0.5 when expecting 0.4 or less". Same unresponsiveness again in the morning as well.

I am now at a point where I am not quite sure what is wrong. Any advice would be much appreciated!

My thoughts are running Prime95 again to see if the 3rd core fails at the same point and also maybe running memtest. Any ideas/suggestions welcome!

[watercooled]

The non-responsiveness sounds like more of a software/driver issue that hardware. Does the system pass stress tests with everything back to stock? Auto-overclockers aren't known for brilliant results, and they often use way too much voltage. Also, something worth bearing in mind (although not the most likely cause for instability), is the Haswell memory controller is rated up to 1600MHz. AFAIK they will generally work at 2400, but this isn't guaranteed, so check with CPU-stock memory speeds too, if you're still getting failed stress tests.

I've known that Gigabyte utility software to cause weird issues, so I'd get completely rid of that for starters.

[Phage]

Yep. Sounds like a poor OC. I'd be trying it at stock.

[benc85]

I haven't taken the stress tests too far yet - although the prime95 failure was done with the CPU back at stock. I did manually revert the bios settings to get it back to default clock speed I am wondering now if I should just clear the CMOS or run through and set all the defaults as per the manual?

To be honest I've been out of the loop on overclocking since I departed from Socket 775 with the whole unlocked multiplier approach, so I probably need to find a proper guide and take the time and do it manually like I used to.
I have never been that keen on MB vendor utility packages, will kill all of that off this evening and see if it helps!

[watercooled]

A CMOS clear wouldn't hurt, to be sure of stock settings, voltages, etc. I'm not sure what that software would modify, but it's sometimes possible to change settings which have no reference in the BIOS interface.

After doing so, be sure to check stuff like SATA mode is set correctly, of course.