3930K Prime stable but not POST stable

[iB CoMpL3XiTy]

Hey guys.

I'm doing a lot of rendering at the moment, a single ray tracing render can take 10 hours so I decided to overclock from stock to 4.2Ghz, I ran Prime95 for 12 hours with 1.260V and a max temp of 80C using a Corsair H60. My RAM is running at stock speed/timings/volts.

The problem is that when I start my computer from a cold boot it will power on for a few seconds, then restart, then power on telling me that the overclock failed and will give me an option to load optimized defaults or enter BIOS.

I can enter the BIOS and save and exit and it will successfully boot at 4.2Ghz and will be stable.

So how can the overclock be stable through prime95 for 12 hours but fail to post?

CPU: Intel Core i7 3930K
RAM: 4 x 2GB Crucial Ballistix Elite 1866Mhz CL9 1.65V
Motherboard: Gigabyte X79 UD3 F7 BIOS
Cooling: Corsair H60
PSU: XFX 1000W Pro platinum

Thanks guys.

 

[mmj_uk]

Are you running the memory at 1866mhz? I would try setting it to 1600mhz if so and see if that helps.

 

[iB CoMpL3XiTy]

Are you running the memory at 1866mhz? I would try setting it to 1600mhz if so and see if that helps.

Thanks, Any suggestions to alter any settings will have to wait until tomorrow as my PC is half way through a render. I'll try 1600Mhz tomorrow, so do you think it may be a problem with the RAM or the CPU's IMC?

 

[mmj_uk]

It could be.

3930K officially supports memory up to 1600mhz, so it's possible that 1866mhz memory is causing some sort of incompatibility/cold boot bug, it may not help but worth trying.

 

[nalla]

have you updated your bios to f9, i have heard of problems on that board with earlier bios, but which one i dont know, but i know of people who have said they updated to f9 and problems were solved.

im getting the same m/b on friday and will be updating bios first thing.

oh and it shouldnt be the memory speed as i have heard of the gigabyte m/b working with up to 2400mhz memory, i will look for the post that says this.

 

[8 Pack]

You need to show more settings than this as it could be several things causing your problem. I think its memory related though. Probably VCCSA , VTT or slight differences in timings during boot up memory training.

 

[eyetrip]

Best of luck to you.

Tried a UD3 myself but it was terrible.

But do try upping your volts to 1.3V and I remember bumping up the VCCT (I think) helped me with certain stability issues.

I can't remember exactly how much I upped the VCCT though.

 

[andybird123]

I run my ram at 1866 with no issues whatsoever... let me check my settings tonight and I'll post back

I used the SandyBridge OC guide to work mine up - you just have to be a little more conservative and keep the heat in check, but the guide I used says to leave everything stock, then set XMP or however you are clocking the memory, then adjust IMC and VCCT until the memory is 100% stable, THEN go after CPU clocking

it sounds a little like you've tried to rush at it and just change a whole bunch of settings all at once which is not the way to get a stable clock

the UD3 does suffer from Vdroop quite badly so you have to set it higher in the bios and then use CPU-Z to check what it's actually getting... mine is set to 1.4v in the bios, which it occaisioanlly hits on idle, but in use it never goes above 1.35 and 75C on a SilverArrow

the H60 is pretty rubbish for a 3930K, you either need a decent air cooler (£50) or a proper watercooling loop (£150)

 

[iB CoMpL3XiTy]

The only settings I've changed are Vcore, CPU multi, LLC at 60% (max with this BIOS) and memory settings set at what they are rated for.

Last night I changed the RAM speed to 1600Mhz but still had the same issue this morning, I'll flash the BIOS later and see if that helps.

@andybird123 yeah the H60 is rubbish for a 3930K but was all I could afford at the time, I did have a custom water loop worth £300 but had to sell to cover the rent. Rendering at 4.2Ghz gives temps of 78C which is alittle high for my liking.

My Vcore is 1.305V in the BIOS giving a reading of 1.260V under load (any lower and it'll fail prime95 after a few hours)

 

[8 Pack]

VTT and VCCSA are critical for the CPU's onboard memory controller. This is nothing to do with the sticks themselves. What VTT and VCCSA you at???

 

[iB CoMpL3XiTy]

VTT and VCCSA are critical for the CPU's onboard memory controller. This is nothing to do with the sticks themselves. What VTT and VCCSA you at???

Not changed them, they're on AUTO.