Infinite loop restarts, quickdiag LED's flashing CPU then DRAM - PC will boot properly with only one RAM stick

[reallyconfusedjosh]

Hi all,

PC Specs:
CPU - Intel Core i5-8600K CPU @ factory settings (4.3Ghz turbo)
MOBO - MSI Z370 -A PRO -----------------> NOW CHANGED TO Gigabyte Z370 Aorus Gaming K3
RAM - Corsair Vengeance LPX 2x8GB @ 2400 Mhz - DDR4
GPU - PNY Nvidia GeForce GTX 1070 XLR8 Gaming OC 8GB (the 3 fan version)
PSU - Corsair TX650M Semi modular, 80 PLUS Gold, 650 Watt
Cooling:
CPU - Noctua DH-D15S
2 output 120mm case fans rear and top
2 Input 140mm filtered case fans on front.

Case: NZXT S340 Elite

Harddrives:
Crucial 275GB SSD
Seagate 2TB 7200 TRM


After shipping my PC from France to the UK, I noticed i was getting bluescreens/freezes sometimes after start-up from leaving it on sleep overnight. These problems compounded into the PC no longer booting at all after a forced restart because of a freeze approx 3 days after the first incident. I would turn on the power, I would get a white light on the CPU led, then a white light on the DRAM led, then the power would cycle off and the process would repeat, every couple of seconds, until i turned off the power supply.
I built this system back in February of this year, it was working fine before shipping it. I stripped it down to individual components and rebuilt it, which didn't fix the issue.

Assuming something was wrong with the RAM, I removed a stick. Hallelujah, it boots. I tried swapping the stick I had installed with the other stick i removed, it still boots. It wont boot with 2 sticks in though. It can't be faulty RAM because both sticks work independently.

My immediate assumption was "I messed up the motherboard with the vibrations during shipping". I reseated the CPU just in case, but it didn't fix the issue, so I bought a new motherboard.

After taking out the old mobo, installing the new one, putting everything back together, I had both RAM sticks installed and the PC was working fine, its now been 3 days and today my PC froze on start-up from sleep. After forcing a restart, the same issue appeared: cycling LED's from CPU to DRAM, then power cycle and repeat.

I removed the RAM stick in slot 4, no boot, but the power no longer cycles, the system hangs with the DRAM led on. I put both RAM sticks on slot 1&3 : same power cycling problem as originally. I removed the stick from slot 3: PC works fine.

At this point i'm all out of ideas. My only option would be taking it in to a shop to get them to check the CPU for issues, as I don't have a spare CPU compatible with the Z370 chipset.

I'm posting this from the PC in question, with just one RAM stick installed. If anyone has any ideas, I'd love to hear them. Thanks in advance!

EDIT: UP TO DATE LIST OF THINGS I HAVE TRIED:
-Reseating CPU
-New motherboard
-Flashing BIOS to newest available software
-DIMM slot 1 works, DIMM slot 2 works
-DIMM modules both work

Reseated heatsink, untightening it a bit, system now boots with 2 sticks of RAM in it (Slot 2 and 4). Everything looks fine.

3 Hours after this, PC suddenly restarts, no warning, just black screen, quick diagnostic LED stuck on CPU. After reboot, it now flashes CPU - DRAM - CPU - then power cycles and it repeats. Removal of a RAM stick from slot 4 solves the boot problem.

At this point more and more things are pointing towards CPU. I can't discount case shorting or PSU problems though.

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Moderator
Lutfij

 

[Lutfij]

How did you ship the system from point A to point B? If the cooler was attached, I'm assuming some undue force/stress was subjected to the CPU socket/board. You might also want to try and see if a replacement PSU(borrowed from your friend/neighbor) changes the scenario. Please look for a higher wattage unit that has reliable build quality.

 

[reallyconfusedjosh]

How did you ship the system from point A to point B? If the cooler was attached, I'm assuming some undue force/stress was subjected to the CPU socket/board. You might also want to try and see if a replacement PSU(borrowed from your friend/neighbor) changes the scenario. Please look for a higher wattage unit that has reliable build quality.

Sorry about the vulgarity, thanks for editing it out.
Unfortunately, you're most likely correct. I shipped the unit whole in the original case box with fitted polystyrene, with cooler and GPU attached. Not the smartest move I've ever made. That why my first call of port after confirming the memory seemed OK was buying a new motherboard.

I'm confused as to your comments about the PSU though, is the Corsair TX650M not a good unit, and is 650W not sufficient for my build? If you have any recommendations for alternatives I'll gladly take them!

 

[reallyconfusedjosh]

After more serious testing, it turns out the boot I got with ram stick B only turned out to be a fluke. One of the RAM sticks was a dud. Dunno how it happened, maybe static discharge as I was re-adjusting the heatsink after the shipping (it was a bit bent).

But yeah I bought a new kit of RAM and it works fine now with both new sticks, so I'm sending the old kit to corsair to get RMA'ed thanks to their lifetime warranty.