The system runs great under full load for as long as I need it to but when I leave it idle, eventually (usually immediately on screen off/system idle (not sleep/suspend just display off)) it will slide into this endless reboot state.
In this state it will randomly power cycle every few seconds (fluctuates). It will remain in this state until either it completely stops 'trying' or I cut the power to the Power Supply.
When it has 'stopped trying' it's using virtually no power but the motherboard lights are on indicating the board more power then a complete off state (just one LED lit). Nothing is responsive at this point and while the power switch turns it on and off however it never actually boots, initializes USB, or inits display.
If I cut the power, I still have to manually toggle the power supply switch or else it remains in this dysfunctional state.
- Motherboard: ASUS Z97I-PLUS
- CPU: Intel i7 4790k
- RAM: Kingston HyperX 1600MHZ 8GBx2
- PSU: SilverStone Technology SX800-LTI 800W, SFX-L, 80 Plus Titanium
- AIO Liquid cooler that maintains about a 26C average idle to 50C full load
- I've already gone as far as RMAing/replacing every component:
- 2 Motherboard RMA's
- 4 Power Supplies
- 1 CPU RMA
- 1 different known working set of memory
- 3 different storage devices:
- USB 3.0 HDD
- M.2 SSD
- SATA SSD
- Added a 700VA 420W UPS inline which I've tested runs the PC on it's own
- Full range of PC power usage is 40-150W max
- Moved it to another outlet in the house that is definitely working for another PC
- Running memtest for around 18 hours
- Disabling all known C-State/Sleep state functions in BIOS
- Running off of a LiveCD (USB)
I'm at my whits end. The issue has remained identical throughout this entire replacement, rebuilding ordeal.
Only thing I can think to do is buy a new/different motherboard model but ITX's are fairly pricey. That or more power supplies...
As it happens, the 2nd Motherboard RMA merely resulted in ASUS resetting the BIOS and sending the same defective board back. Waiting on the new one but I'm putting all my eggs in that basket for now.