Custom Built PC Won't Start

[mahclark]

First thing's first, here are the specs:

CPU: i5 6600k
GPU: GTX 970 EXOC
Motherboard: Asus H110M-A
PSU: EVGA 600W 80+
RAM: 2x8GB Kingston HyperX Fury Black
And then an ssd, an hdd, an optical drive, two case fans and a cpu heatsink (and obviously a case). I presume these items aren't relevant. I am running Windows 10.

My PC booted first time all right and I installed the OS. After that, I have had problems with the power button being unresponsive. I have made a log of most of the events:

Some stuff happened beforehand but I hadn't started the log.

- Start button unresponsive (SBU)
- Remove one RAM stick
- Works
- Shut down & leave over night (SDLO)
- SBU
- Put RAM back
- SBU
- Rotate POWER_SW & RESET_SW front panel headers 180 degrees each
- SBU
- Revert front panel headers back to normal
- Works
- SDLO
- SBU
- Unplug front panel headers and plug them in again
- Adjust optical drive position
- SBU
- Remove one RAM
- Works
- Put RAM back
- Works
- SDLO
- Works
- SDLO
- Works
- 1-2 minutes after playing Just Cause 2, PC is idle. Screen goes black and all fans stop apart from PSU fan. All LEDs on and inside the PC still worked.
- Shut down
- Press power button. Only PSU fan and LEDs work.
- Shut down
- SBU
(a while later)
- Take out RAM (forgot to ground myself)
- SBU
- Replace RAM
- SBU
This is where I am now.

Can anybody see which component is the culprit? This is my first build and am I getting frustrated. Please ask if you need more info. Any help is greatly appreciated.

UPDATE:
- Took out 1 RAM
- Worked
- Had to turn it off instantly using the power button because the cpu fan wasn't fully connected.
- Any combination of RAM thereafter gave an SBU

 

[alexoiu]

Does it work with single RAM installed?

 

[mahclark]

Does it work with single RAM installed?

Sometimes. At the moment, no.

 

[alexoiu]

What happens when pressing the power button? Do all fans spin?

 

[mahclark]

What happens when pressing the power button? Do all fans spin?

Like I said before, SBU (start button unresponsive). So no, the power button does nothing.

 

[alexoiu]

Then disconnect the button wires from the board and try shorting the 2 pins with a screwdriver. See if still no go.

 

[mahclark]

Then disconnect the button wires from the board and try shorting the 2 pins with a screwdriver. See if still no go.

Tried it, still no response from the power button.

 

[alexoiu]

Then try testing the power supply: https://www.youtube.com/watch?v=5FWXgQSokF4
See if a fan connected to it does spin.

 

[mahclark]

Then try testing the power supply: https://www.youtube.com/watch?v=5FWXgQSokF4
See if a fan connected to it does spin.

Thank you. I didn't have the correct cabling to connect my case fan to the PSU so I tried the test without it. The PSU fan did come on. I presume that means that the PSU is working and the issue is probably the motherboard(?). Will I have to buy a brand new one/get a refund or is there a quick fix?

 

[alexoiu]

Try removing the CPU power cable from the motherboard (leaving the 24 pin one connected only) and starting the board. See if the case fans do spin.

 

[mahclark]

Try removing the CPU power cable from the motherboard (leaving the 24 pin one connected only) and starting the board. See if the case fans do spin.

Okay, I've tried it without the CPU power cable (with every other cable connected) in and nothing happens when I push the power button. This eliminates the CPU. What next?

 

[alexoiu]

Try starting the board outside the case, for ruling out a short. If still the same, it looks like a defective motherboard.

 

[mahclark]

Try starting the board outside the case, for ruling out a short. If still the same, it looks like a defective motherboard.

I've just realised the main motherboard power cables weren't connected properly. I tried it without the CPU power cable and the fans do spin. This means it's the CPU which is faulty, right?

 

[alexoiu]

What happens when both 24 and 8 pin power cables are connected?

 

[mahclark]

What happens when both 24 and 8 pin power cables are connected?

Without the CPU power cable: all fans start spinning.
With the CPU power cable: power button is unresponsive and no fans spin.

 

[alexoiu]

Is the board outside the case?

 

[mahclark]

No, shall I try it or can I rule out a short because it worked when the CPU power cable wan't connected?

 

[alexoiu]

Yes, it would be better to test it outside. Better control too. If still no go, try removing the CPU and checking the CPU socket. See if any bent pin. You can post a picture of the socket here.

 

[mahclark]

Yes, it would be better to test it outside. Better control too. If still no go, try removing the CPU and checking the CPU socket. See if any bent pin. You can post a picture of the socket here.

Okay, I've slid some cardboard underneath the motherboard. When the CPU power cable was unplugged, all fans came on. When the CPU power cable was plugged in, the fans turned on, then went off and turned on again. Here is the socket image - it looks alright.

 

[alexoiu]

Pins look ok. Assuming that the power supply does work, then it could be a CPU issue.
"When the CPU power cable was plugged in, the fans turned on, then went off and turned on again" Was RAM installed, or not? If installed, then test without RAMs. See if fans constantly spinning.

 

[mahclark]

Pins look ok. Assuming that the power supply does work, then it could be a CPU issue.
"When the CPU power cable was plugged in, the fans turned on, then went off and turned on again" Was RAM installed, or not? If installed, then test without RAMs. See if fans constantly spinning.

Something different happened this morning. I still have the cardboard underneath the motherboard and both RAMs are installed. The fans start spinning both when the CPU power cable is and isn't connected and when it is connected, it boots like normal. However, this doesn't mean it is fixed because it worked previously with the CPU power cables connected and then failed later. It seems to be random whether it works or not when the CPU power cables are connected.

 

[alexoiu]

Try testing for a while and see if issue reoccurring.

 

[mahclark]

Try testing for a while and see if issue reoccurring.

Okay, each time I've tried it with the CPU power cable unplugged, it has worked, but it has only sometimes worked with the CPU power cable in. This means I need a new CPU, right? I will keep test over the next few days anyway just to make sure.

 

[alexoiu]

I'd RMA both board and CPU.

 

[mahclark]

I'd RMA both board and CPU.

RMA just means return them, right?