Question Random Power Off Under Full Load - No Error Codes ?


Jun 17, 2014
Recently changed my graphics over to an EVGA SC2 Hybrid 1080ti and have started to experience full system reboots under load.
GSKILL 2666 ram (4x4GB)
1x SSD, 6x HDD
650w Coolmaster V series
EVGA SC2 Hybrid 1080ti
Intel AX WiFi card
ASUS Prime Z270-A

Reboots only occur when system is under full load (intense gaming or video encoding) as far as I can tell - once at full load, shutdowns appear to be relatively random. No BSOD or any other logged errors present in the windows log, other than an error notifying that the system powered down unexpectedly. I'm thinking it is likely the PSU, but I don't have a spare rated high enough to do a test swap. Don't really want to buy one if that isn't the issue. Only change in hardware is the new graphics card, as mentioned. The card it replaced was an old 950 (which used much less power). The 650w unit I have SHOULD be more than enough and it's only 5 years old, but I can't think of anything else it could be.

Any thoughts would be appreciated!


A five year old PSU is, in my mind, almost an immediate suspect.

Especially if the PSU has been heavily used for gaming.

And with problems seemingly occurring "under full load" that is all the more reason to suspect the PSU.

The PSU was likely able to keep up with the power demands of the original GPU.

Once the new (more power demanding) EVGA GPU was installed the PSU crossed a threshold where the PSU could/can no longer keep up.


Best Power Supplies of 2021 - Top PSUs for Gaming PCs | Tom's Hardware

Not with the immediate intent to purchase a new PSU.

Use 2 or 3 of the calculators along with your own manual total to determine the applicable wattage size for your computer. If a component uses a range of watts then use the high end value. (Also: do I understand correcly that your computer has 6 HDDs - please verify).


Note the suggested PSU size of 600 watts.


Given your description of the cause. Plus that it's a sudden power loss without error with a power event warning. It sounds like a PSU being overloaded. Perhaps just barely overloaded. So it takes a particularly heavy load event to overheat. Such as the PSU plus CPU at near full load for a few minutes.

Which wouldn't surprise me given that the PSU scrapes the low side of what should be paired with that GPU. Add to that six hard drives and a few years wear on a passable quality PSU. It's likely time for a heavier duty unit.

The PSU is probably still fine for use elsewhere. It's just a bit light for all the hardware being connected.

Edit: @Ralston18 got in just before me. At least you have another confirmation of the PSU as the most probable cause.