i5-6600K issue?

-zax-

2[H]4U
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Jul 21, 2004
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2,083
A friend had me build a PC for him over a year ago and recently asked me to look at it because it won't boot up. I found that the computer will hard lock even in CMOS assuming it will even make it that far. Sometimes when turning the PC on, the lights on the motherboard will light up but and nothing will display on screen.

General specs:
CPU: Intel i5-6600K
MOBO: Gigabyte GA-Z170XP-SLI
RAM: 2x8GB GSkill DDR4 PC3200 (PN: F4-3200C16D-16GVK)
GPU: Asus 980ti STRIX
HEATSINK: Corsair H110i GTX
PSU: Seasonic 1000W

I pulled everything off of the board except CPU, RAM, and the H110i. I used the onboard video to boot and it still locks up even in CMOS. I don't have any spare Skylake parts including DDR4, so I tried swapping the memory modules into different slots as well as trying only 1 module in more than 1 slot.

I also tried a different PSU which was my spare Corsair AX850. When testing the spare PSU, I had the board pulled from the case so it was completely isolated minus the CPU, RAM, and heatsink.

I originally thought it was the motherboard... however, unfortunately, my friend is in a rush as he has tax information on this computer and doesn't want to wait for an RMA on the motherboard. So I ordered a new Asus Z170-A and swapped it with the original Gigabyte board. The computer exhibits the exact same behavior with the new motherboard in place.


Sometimes when attempting to boot the PC, I will get normal post beeps from the speaker I plugged into the motherboard header. There are also times when I boot the PC that I will get absolutely nothing from the speaker like it's locking up before it gets to post. If I pull the memory modules, it will beep indicating they're missing.


I believe I have isolated everything but RAM and CPU at this point. Unfortunately I do not have a spare of either one....

Which item do you think is the culprit? I'm leaning toward the CPU considering that the PC behaves the same regardless of which ram scenario I try. I'm not sure what the chances are that both sticks of RAM could go bad at the same time, but I've been fooled before.

I suppose worst case scenario, I can buy a single stick of DDR4 for around $35 and try that, however I'd hate to dump more money into this thing considering my first guess of replacing the motherboard was wrong...



TLDR:
1. Friends computer locks up even in CMOS
2. Isolated everything but board, CPU, RAM, and heatsink
3. Tried a different PSU and had board isolated from case
4. Tried memory in different configurations, including only 1 stick
5. Replaced motherboard, but still does the same thing
6. Guessing it's CPU, but not 100% sure
 
Last edited:

-zax-

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My bad, I thought I wrote that, but I didn't... I'll update the OP.

I have tried my spare Corsair AX850 and had the motherboard isolated from everything including the case...
 

-zax-

2[H]4U
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Messages
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Definitely not a temp issue I'd imagine as well. When the PC does get into CMOS, the pump shows a working RPM, the fans are spinning on the radiator, and the temps according to CMOS before it locks up are around 23C.
 

DrLobotomy

Supreme [H]ardness
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May 19, 2016
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Did you examine the chip's underside to see if maybe something got stuck on the little contacts? Other than that, it would seem you have done all you can do.
 

-zax-

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All looked good physically on the CPU.

Called my friend up and he wanted me to just order a new CPU regardless. Guess I'll find out on Wednesday if it was that or not...
 

-zax-

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I figured I'd throw a quick update in...

The CPU was bad. Going to RMA it and he's going to build a second computer now with the rma'd CPU and the new motherboard.

Thanks for the extra ideas.
 

DrLobotomy

Supreme [H]ardness
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May 19, 2016
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Glad you got it figured out. At least you get a new part. Sucks when you have to pony up.
 

-zax-

2[H]4U
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Jul 21, 2004
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I've been building PCs since the late 90's, and this is the first bad CPU I've had.

I can't recall the amount of bad motherboards, RAM and hard drives I've had in that time frame though...
 
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