Question Strange boot loop

[Ivan Grozny]

Hi,
I have a very bizzare boot loop problem and it's driving me crazy. It started when I replaced an old GPU with a new one, and then dissapeared when I reversed back to the old one.
Let me start at the beginning. My initial old setup was this:
Motherboard: Gigabyte Z68AP-D3
CPU: Intel i5-2400, 3.10GHz, 4 cores
GPU: XFX RADEON HD 6870 1Gb
RAM: 4 x 4 Gb Corsair vengeance
HDD: WD500
SSD: Samsung 860 EVO
PSU: CHIEFTEC GPS-550A
Monitor: U2412M

Because I couldn't play any newer games, I wanted to breathe some new life into this PC before it got completely outdated. So I got a Sapphire RX 570 4Gb dual pulse and replased the old XFX HD 6870. I did a by-the-book installation: removed the old driver with DDU, and installed the up-to-date new one for the new GPU. So, everything was working fine for 2 days, and then this problem started happening: I turn on my PC once a day and let it run until the evening when I shut it down. Every 2 or 3 or 4 times I would turn it on, and then a couple of seconds after the first beep and into the first pre-windows screen (I don't know what's it called, it's the screen during which you can get into the BIOS), it would shut down, and then stay that way for 3 or 4 seconds, then turn on again, and then repeat everything. It would keep boot looping forever (probably), but then I shut down the PSU and wait for half a minute and turn it on again. This would resolve the boot loop most of the time, but sometimes I had to repeat it a few times to get past the point of shutdown.
But here's the crazy part: when it would successfully pass that point of rebooting, the PC would be working just fine. Perfect, that is. I even did a stress test on the GPU, and it worked perfectly. So, there were no issues past that point.
But, sometimes the problem would occur after extended time in sleep mode, but not always.
So, here's what I tried to do, at first:

• tested all the RAM sticks and slots – all were good
• checked all of the power connections – all were good
• blew the dust off, tho there wasn't much of it
• removed the BIOS battery
• updated BIOS to the newest version

All of this didn't resolve the issue. So my conclusion at the time was that it was the PSU. So I replaced it with a brand new Corsair VS550. Still no luck. My final thought was that the GPU was faulty, so I returned it to the store. A month later they e-mailed me that I could chose to have my money back or that they could send another GPU of my choosing in the same price range. So I chose XFX RX 570 RS 8GB XXX Edition.
After I installed it, guess what. The same problem started happening again. Thats when I re-installed the old GPU (XFX RADEON HD 687), and everything worked fine again.
So I'm out of ideas.
In my opinion, there shouldn't be any reason for a RX 580 not to work with my PC.
Please help.

 

[clutchc]

Unless I missed it, did you try the PC using just the iGPU? No card in the PCIe x16 slot.

 

[Ivan Grozny]

Unless I missed it, did you try the PC using just the iGPU? No card in the PCIe x16 slot.

If you mean the built-in GPU, no, I didn't try that. I didn't think it was necessary, because when i re-installed the old GPU, everything worked fine. I forgot to mention that in the original post, I'm sorry (I corrected that). I guess it's an important piece of the puzzle.