PC build keeps restarting every 3 seconds after CPU power is plugged in

[tomizzo11]

Hi there,

I'm new to the PC building world but have experience with circuit design and custom electronics. I've recently run into an issue after assembly where my build gets stuck in a reboot loop (everything turns on for 3 seconds, shuts-off, turns on for 3 seconds, shuts-off, repeat. etc.) All the enclosure fans revs up too while it is on.

Here are my components:

Enclosure: Corsair Obsidian 250D
Motherboard: ASRock - H370M-ITX/ac Mini ITX LGA1151
CPU: Intel - Core i5-8400 2.8GHz 6-Core Processor
Memory: GeIL - Pristine 16GB (1 x 16GB) DDR4-2400 Memory
Power: EVGA - SuperNOVA G3 750W 80+ Gold Certified Fully-Modular ATX Power Supply
Storage: Samsung - 860 Evo 250GB 2.5" Solid State Drive

Note: I have not selected a graphics card and am hoping to just use the integrated graphics in the core i5.

I had selected these component to ensure they would be compatible. I've just recently confirmed that via PC Part Picker's website.

Timeline of my troubleshooting efforts:

• 
  ■ After initially installing everything, I decided to remove power from devices that didn't need to be powered in order to isolate the issue.
  
  ■ I removed power from SSD. The infinite reboot cycle persisted.
  
  ■ I removed all auxillary connectors (USB, audio, etc.). Infinite reboot cycle persisted.
  
  ■ I removed power going from the EVGA power supply to the CPU power input (i.e. not the motherboard input). This is the ATX 12V Power Connector (ATX12V1) per the user manual.
  
  Link to motherboard manual - http://asrock.pc.cdn.bitgravity.com/Manual/H370M-ITXac.pdf
  
  ■ After removing the CPU power input, the infinite reboot cycle stopped.
  
  ■ After plugging the CPU power back in, the infinite reboot cycle came back.
  
  ■ Seeing as the problem was directly related to powering the CPU, I assumed there was something incorrect with how the chip was sitting in the socket. I removed the chip and inspected the socket for bent pins etc. It looked okay and re-installed it. However, the infinite reboot problem persisted.
  
  ■ So to go more in depth on the infinite reboot problem, when it occurs, the fans (all enclsoure fans and CPU fan) speed up very fast and then the power shuts off. Two things that I could theorize on this: 1) the CPU thinks its very hot. 2) the CPU power is somehow shorting and providing power the fans and giving them a full voltage of something else.
  
  ■ So let's assume I'm delivering bad power, I did find the CPU power cable to be rather odd. The EVGO power supply provides a cable that features an 8-pin ATX12V connector on the PSU end, and a 4x2 EPS connector on the motherboard side.
  
  However, the motherboard actually features an 8 ATX12V female connector (i.e. not a 4x2EPS connector). After reading some reviews online, the general consensus is that you can use a 4 pin connector to power the 8 pin socket on the ATX12V. This is essentially what I've been doing.
  
  Illustration:
  
  EVGO (ATX12V 8-pin): (ATX12V 8-pin)------------------------( 4x2 EPS): (ATX12V 8-pin) MotherBoard
  
  This area was the foggiest during the build and is only connection that I've found where I can trigger the infinite reboot cycle. Thus it sticks out. Would there be an issue with me using one of the 4 pin cable connector to the power the 8 pin connector on the motherboard?
  
  ■ I have not pulled out a multimeter to check current draw or anything like that yet, however, it seems plausible that my CPU power supply is creating a short circuit and thus faulting the power supply. I've verified that there the motherboard is not shorting against the case, however, I have not attempted to breadboard the system yet.

Summary: My new PC build is stuck in an infinite reboot cycle. I can trigger this phenomenon by plugging in the CPU power. I'm curious if anyone has any further troubleshooting tips, is familiar with the ASRock motherboard, or has any other general advice. If I can progress any further, I will probably go ahead and contact my vendor to get replacements on the motherboard and power supply and CPU.

 

[RememberThe5th]

Motherboard standoffs?
Have you tried breadboarding?

 

[SgtScream]

Does this issue happen as soon as power is provided to the system or does it happen after you push the power button?

 

[tomizzo11]

Motherboard standoffs?
Have you tried breadboarding?

The Obsidian 250D case has integrated stand-offs. I inspected the underside and it doesn't appear that anything is touching.

I just found out that breadboarding is a common troubleshooting strategy, I will attempt that tonight and report back.

 

[tomizzo11]

Does this issue happen as soon as power is provided to the system or does it happen after you push the power button?

This occurs when I press the power button. I've experimented with unplugging the front panel reset switch connection and I believe that wasn't an issue. I will double check tonight that the reset switch is plugged in correctly.

When I unplug the CPU power, all the fans will turn on and spin and the system will not reset. Once I plug in the CPU power, I can hear the fans rev up to faster than what they had done previously.

 

[scout_03]

did you remove the plastic tab under cpu cooler also cpu fans plug in cpu header no 1 .

 

[tomizzo11]

did you remove the plastic tab under cpu cooler also cpu fans plug in cpu header no 1 .

There was a plastic piece in the CPU socket on the motherboard, however, I don't recall seeing any other plastic attached to the CPU fan that came with the chip. I will check and report back tonight.

I installed the CPU fan to the CPU_FAN_1 pin header.

 

[scout_03]

if you did remove it from cooler that ok another thing did you use thermal paste between cooler and cpu or the preapply one .

 

[SgtScream]

Does this issue happen as soon as power is provided to the system or does it happen after you push the power button?

This occurs when I press the power button. I've experimented with unplugging the front panel reset switch connection and I believe that wasn't an issue. I will double check tonight that the reset switch is plugged in correctly.

When I unplug the CPU power, all the fans will turn on and spin and the system will not reset. Once I plug in the CPU power, I can hear the fans rev up to faster than what they had done previously.

Keep the CPU power cable to the motherboard unplugged. Unplug ALL of the front panel I/O. Then plug the CPU power back in and see if the issue replicates.

 

[tomizzo11]

if you did remove it from cooler that ok another thing did ou use thermal paste between cooler and cpu or the preapply one .

I just used the thermal paste that came with the CPU. Should I apply my own?

 

[scout_03]

no it if was having paste on that is good .

 

[RememberThe5th]

I would point my finger at motherboard.

 

[tomizzo11]

Does this issue happen as soon as power is provided to the system or does it happen after you push the power button?

This occurs when I press the power button. I've experimented with unplugging the front panel reset switch connection and I believe that wasn't an issue. I will double check tonight that the reset switch is plugged in correctly.

When I unplug the CPU power, all the fans will turn on and spin and the system will not reset. Once I plug in the CPU power, I can hear the fans rev up to faster than what they had done previously.

Keep the CPU power cable to the motherboard unplugged. Unplug ALL of the front panel I/O. Then plug the CPU power back in and see if the issue replicates.

I would point my finger at motherboard.

After breadboarding the system, it still experiences the fan rev up infinite reboot cycle issue. This occurs as soon as I plug the CPU power in.

 

[tomizzo11]

Does this issue happen as soon as power is provided to the system or does it happen after you push the power button?

This occurs when I press the power button. I've experimented with unplugging the front panel reset switch connection and I believe that wasn't an issue. I will double check tonight that the reset switch is plugged in correctly.

When I unplug the CPU power, all the fans will turn on and spin and the system will not reset. Once I plug in the CPU power, I can hear the fans rev up to faster than what they had done previously.

Keep the CPU power cable to the motherboard unplugged. Unplug ALL of the front panel I/O. Then plug the CPU power back in and see if the issue replicates.

I just performed this test and the problem persists. I've left the CPU power unplugged, I then booted it up via the front panel I/O. I then removed the front panel I/O from the motherboard. I then proceeded to plug in the CPU and it started doing the fan reving infinite boot cycle.

 

[RememberThe5th]

Thats what im telling you, since you plug power for cpu, the crap happens, either bad contact between socket and cpu, bad VRMs, or worst case cpu.
Test cpu in another system. Just in case.

 

[SgtScream]

I agree. Contact Asrock for warranty service.

 

[zebarjadi.raouf]

RAM/MB/CPU/BIOS can cause an infinite loop. No way to know for sure without changing parts one by one to test. I usually borrow from my friend. Contacting Asrock should fix it but it usually takes time.

Try clearing CMOS and changing RAM slot while the PSU is not connected to find out that it's probably not the RAM/BIOS.

 

[saptadeep_nath_58]

It can be your hard drive or your motherboard, as hard drive can have an incorrect registry or there is some sort of problem in the motherboard.

 

[kirsion]

I have the same exact problem, what was you solution?

 

[USAFRet]

I have the same exact problem, what was you solution?

Please start a NEW thread for your particular situation. Your components are not "the exact same".