Is there something wrong with my CPU/Mobo?

ironmysox

ironmysox

ironmysox

Associate
Joined
18 May 2009
Posts
280
Location
Gloucester
Hi OCUK community,

I'm having a bit of a mare with my rig at the moment, see specs below;

Microsoft Windows 10 Professional
Intel Core i7-8700K
ASUS TUF Z370-PRO GAMING Latest Bios 2102
Noctua NH-U12S with 2 fans
Superflower 1000W Platinum
2 x Corsair CMR16GX4M2C3000C15 8192 per stick
Sapphire 5700XT Nitro
EVGA Nu Audio Soundcard
Samsung Electronics SSD 960 NVMe PCIe SSD
Samsung SSD 850 EVO 1TB

I have been running it at default settings, so flash new bios, clr CMOS with Jumper, Set it to XMP and configure fan profile and onboard devices. Now I installed Hardware Info for the first time and I noticed on desktop my core voltage was showing vcore 1.5. All C states are on, Balanced power profile in windows etc. So I installed AI Suite just to see what it reported and it was the same as Hardware Info. Then I tried CPU-ID, Aida 64, all the same. So I reset bios (I must add vcore in windows is 1.136) , basic configuration again and booted into windows. It started off at 1.3vcore, then hit 1.5 again then crept down to 1.35.

I decided to format and do a minimal install just in case something was messing things up, same result. I must add, temps seem ok, 35oC at the mo and the vcore is 1.344.

I decided to try and set it manually and also all cores at 47 as the default is per core. After watching many videos including der8auer's tutorial I decided to try to get it stable at 47. I'd be happy with that but for some reason my system just wont go there. I can boot into windows no problem but OCCT and Prime both fail. I set the vcore manually and I thought I would start with 1.3. Instant fail on all stress tests so I tried 1.32, didn't fail as quick but still failed. Went to 1.35, lasted and hour this time then failed. Went up to 1.38, 2 hours in then fail. I must add Temps are still ok even in the midst of torture testing. I'm reading people getting 4.9 on air at 1.32 - 1.35!!! Have I just got a dog of a chip do you think? I have tried alternative memory as I have some here, made no difference. I have ordered a new PSU form OCUK not that it will make any difference??? Could it? I've ordered it because my Leadtek is so bloody big I wanted a smaller one, not specifically because of this issue.

Any advice much appreciated.
 
Webzta said:
Not all CPUs are the same, my 8700k does 4.8 @ 1.375V from memory. I think the ones that were hitting higher speeds with lower volts were early batches, then later down the line they were binned for 8086k?

Mine and a friends bought around the same time both perform the same.
Click to expand...

Thanks for the reply. I might up the volts then to match yours. The more I've read the more I've come to understand the term silicon lottery.

I'd never heard of the 8086k so I'm going to have a quick Google on that!!!

I will post my results once I've had chance to have a fiddle with my bios
 
Update 1: So far so good. 2 hours of OCCT with 0 errors. Cinebench ok, tried a couple of games, all ok. My vcore is showing 1.392 under full load and my temp went up to 77. I'll do the P95 test later and if all goes well will keep dropping by .5 until unstable!!!
 
Update: Prime 95 fails every time. I even upped the volts to 1.45 just for testing, LLC at 7, no xmp, all at stock and it fails at 4.8. So far into 5 hours of 4.7 at 1.4 and its ok. At 1.35,6 & 7 it fails within the hour. Yikes!!!!!
 
Webzta said:
What is your ram set to? Have you ran CPU stock and tested your ram to make sure there are no issues with that?

Not heard of any 8700s that can't do 4.8 easily.
Click to expand...
I ran memtest and all came back fine. I've even bought another PSU, a Seasonic 850W Plat but still the same. I'm at 4.7 at the mo, prime tested for 10 hours but at 1.38v, any lower and it fails. Bad chip maybe? Mobo maybe? CPU at stock settings is fine, clrd CMOS, set to xmp no other changes. The only thing is my voltage even at stock ranges from 1.3 to 1.5 even when just sat on desktop. That's at stock BIOS settings (optimal defaults).
 
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