[SOLVED] PC stuck in restart loop after connecting CPU to power on motherboard ?

[Al_Bie-04]

Hi everyone,

My mate bought a prebuilt about a year ago, and lately he came with a problem of the PC being stuck in a restart loop.

I took the parts out, including the motherboard, and started slowly rebuilding it and testing it after each connected plug. I soon found with only the 24-pin connected, it works perfectly fine (I tested this with a chassis fan connected and it wasn’t looping, but instead was just constantly on). I was soon able to discover that with the CPU being installed, it’s still fine, but once I connect the 4-pin CPU cable at the top of the motherboard too, then that is what is the source of the looping.

Specs:
Motherboard: ASUS Prime H410M-A
CPU: Intel i5-10400f.
PSU: CoolerMaster MWE 500 (but I know this isn’t the issue as we’ve also tested with a brand new RM750x).

I’m stuck between it being the CPU and motherboard really. Is there a way to possibly narrow this down even more, or try to fix completely? Note that I’ve replaced the CMOS battery as well as cleared it using the 2 pins.

 

[Aeacus]

Is there a way to possibly narrow this down even more,

Yes, if you have 2nd, known to work and compatible CPU and MoBo, so you can test both individually. Otherwise: No.

I soon found with only the 24-pin connected, it works perfectly fine

MoBo doesn't work at all without CPU. And without CPU being powered by 4-pin 12VEPS, you can't conclude MoBo working "perfectly fine".

It's like when you turn the car engine on, and you instantly assume that the car drives perfectly fine, without ever doing a test drive.

 

[Al_Bie-04]

Yes, if you have 2nd, known to work and compatible CPU and MoBo, so you can test both individually. Otherwise: No.

Yeah unfortunately I don’t which is quite a problem as it’s a bit of a guess between the two.

MoBo doesn't work at all without CPU. And without CPU being powered by 4-pin 12VEPS, you can't conclude MoBo working "perfectly fine".

It's like when you turn the car engine on, and you instantly assume that the car drives perfectly fine, without ever doing a test drive.

Yeah I understand that it won’t actually be able to do anything with it but I mean that it’s not what causes the boot loop after being connected, only the CPU cable along with the actual CPU.

 

[Aeacus]

Most of the times, it's dead MoBo. Though, it could be dead CPU as well but compared to how many dead MoBos there are, in relation of dead CPUs, it's easily 1/100 if not more.

CPUs are very reliable and one of the most reliable component inside the PC. Now, MoBo isn't that reliable and is at the lower end of reliability pole. Then again, with MoBo, it depends a lot of the chipset as well. H410 is lowest 400-series chipset, with least amount of features, and is favored towards cheap end. While B460 and H470 are solid mid-tier and Z490 is top tier chipset. Of course, this doesn't mean that all H410 are bad and only Z490 is good.