Is my CPU faulty - opinions please

[gorcor]

I have a one year old PCS overclocked system running Win 8.1 (Overclocked Intel® Core™i5-4670k Quad Core (3.40GHz @ max 4.20GHz))

It has given no trouble at all until now but it hasn't been worked hard just being used for photo editing and office tasks as well as the usual web browsing emails etc.

iTunes is giving trouble when syncing as it works the CPU at 100% - I checked in task manager when I noticed the fan a lot louder continuously instead of up and down as normal, then after a few minutes it would crash the PC with blue screen and the message WHEA_UNCORRECTABLE_ERROR. I know iTunes is an issue, but thought the PC shouldn't crash just because the CPU is at 100% so I decided to check it further.

Downloaded Prime 95 to test it and CPUID HWMonitor to check the temps. Ran small FFT's first and all 4 workers ran with no errors, the temps on cores 0,1 and 2 were 100 deg C though and core 3 was about 80 deg. After 10 minutes all was still the same so I stopped it and ran large FFT's - within seconds the PC crashed - never got to see the temps. Restarted and ran large FFT'a again - this time workers 1,2 and 3 had fatal errors immediately but worker 4 carried on OK, the temp on the corresponding core 3 was around 89. Idle temps on all 4 cores are between 43 and 48 with core 3 being a couple of degrees cooler than the rest. Cooling is by a Corsair H60 Hydro.

I will report this to PCS tomorrow, but do you think I have a faulty CPU?

Thanks in advance.

 

[steaky360]

Not sure about a faulty CPU maybe just unrefined overclock settings? - I'd try the tests again with the overclock removed, if you get the same results (crash/instability) then maybe your CPU is faulty, if not then its likely the overclock was to blame.

PCS will advise you on further diagnostic tests too I'm sure

 

[gorcor]

Thanks - I'm puzzled as my original post seems to have disappeared!

 

[Rakk]

Thanks - I'm puzzled as my original post seems to have disappeared!

When you are new to the forums, your posts will often get auto-moderated and will not be viewable by anyone until the post is approved, this also applies to edits of posts - which makes your posts seem to disappear until they are approved - it should be visible again now.

 

[gorcor]

It is - thank you.

I'm reluctant to touch the overclock settings unless on the instruction of PCS - it hasn't been changed from their build settings.

 

[keynes]

It is - thank you.

I'm reluctant to touch the overclock settings unless on the instruction of PCS - it hasn't been changed from their build settings.

You don't need to touch it. You can save it as one profile and boot with a different profile without the overclock

 

[gorcor]

You don't need to touch it. You can save it as one profile and boot with a different profile without the overclock

OK, thanks. I will try that this afternoon if I haven't heard back from PCS - have sent a tech support message earlier.

 

[gorcor]

PC Specialist replied suggesting I check tightness of cooler thumbscrews, 3 of them were a bit loose.

Had saved PCS overclock profile and loaded Bios defaults idle temps all 23-25, with Prime 95 small fft core 0, 1 76-77, core 2 74-75, core 3 69-70. With Prime 95 large fft Core 0, 1 65-66, core 2 63-64, core 3 58-59. Core Speed (CPU-Z) 3397 throughout.

Loaded bios PCS overclock profile (previously saved) idle temps all 38-40, core speed 4199. With Prime 95 small fft core speed dropped to 2899-2999, core 0, 1, 2 99-100, core 3 87-88. With Prime large fft workers 2 and 4 fatal error, workers 1 & 3 OK, core 0 99-100, core 2 91-92, cores 1 & 3 cooler as not working.

Seems to me either the overclock settings are unstable or the cpu cooler needs re-seating, or the cpu is faulty if overclock settings should be OK. Please note I have never stress tested the PC until today after the recent problems, so I have no idea if this issue has always been there since new or not.

Does this point to a particular fault/component failure? The fact that Prime large FFT's always gets fatal errors from two or three cores is a concern - it does this before the temps have had a chance to rise so it's not caused by overheating.

 

[gorcor]

Latest news on this is that PCS are sending me some thermal paste to re-seat the cooler block on the cpu. I know how to do this having built my last few PC's (except this one - I was lazy and got PCS to do it!). Hopefully this will result in better cooling and even temperature on all 4 cores.

In the meantime I have (as detailed above) ran stress tests with the bios in default settings (3.4ghz max 3.8) and compared results to the same tests at overclock settings.

I am concerned about 2 things resulting from the stress tests above - running large fft's at overclock settings always results in two or three cores having fatal errors, and sometimes just crashes the PC - not sure if this is due to heat or not but it seems unlikely as it happens instantly rather than after running the test for a bit. Also, I have noticed at overclock setting the core speed at idle is 4199 as it should be, then goes quite low during stress testing (around 2900) - even on the small fft's where all four are working, but at default setting (no overclock) the core speed stays where it should be, variable at idle and at 3399 or so under stress test.

Does anyone know if it's normal for the core speed to drop at overclock settings? If not what might be causing it?

Thanks.