A 30-month-old Seasonic 750 Gold Modular

[BonzaiDuck]

I've been trying to troubleshoot an intermittent "instability" problem that had been occurring every 5 to 7 days -- usually an unannounced reset -- occasionally a BSOD.

Both the CPU (SB i7-2600K) and the RAM (DDR3-1600 @ 1866) were OC'd. I attempted to "correct" the problem by tweaking the BIOS, but that doesn't eliminate it. I began to suspect the RAM, so I tuned them down to their DDR3-1600 spec and latency timings. They had run at the 1866 setting with the stock 1.5V spec. These were two 2x4GB kits of the same. I must wait a few more days to see if that was the source of the problem.

The PSU was a Seasonic Modular 750 Gold unit. For the last several years, I have settled on Seasonics -- more inclined to get them as "Seasonic" than the rebadged units like the PCP&C "Silencer" and other incarnations.

I couldn't imagine this PSU headed to failure in 30 months. Haven't tried measuring voltages with the multimeter, but the software measurements show the voltages as they were when I first installed the unit. For a 750W, it seldom uses more than 200 or 300. [So the system is probably "overpowered."]

Today I was fiddling with the BIOS settings, made a change and rebooted. I suddenly heard a faint sound that reminded me of a fan that wouldn't spin up. The fan was a Sharkoon 140mm, and I know the amperage requirement on those is low -- definitely less than 0.2A. I opened the case: the Sharkoon had been plugged into the mobo's "PWR_FAN" plug, and had always spun up to between 850 and 900+ rpm. And of course, it was sitting in there trying to spin up -- but couldn't. My other fans were running fine.

I rebooted, and everything was fine again. So . . . I'm wondering . . . about a lot of things -- PSU among them. Thoughts?

 

[Torn Mind]

Yes, it could be your PSU. It also could be your motherboard, since the power delivery system continues from the PSU into the motherboard.

Fans are powered by the 12V rail, so the inability for it to start up could certainly be some sort of power delivery issue there, or it could be something wrong with the BIOS chip communicating with wherever the board controls the fan power delivery.

And bad RAM could also cause a sudden BSOD. Have you looked at whocrashed logs yet?

 

[readymix]

just throwing it out but the last stability problem I had was caused by monitoring software.

 

[_Rick_]

It could be anything - even a combination. It does smell mostly like a power issue, but those can stem from up or down the chain... PSU issues are the most probable, from my experience.
Getting a PSU and swapping that sometimes even helps at curing a dying mainboard for a few more months.
I'd recommend getting a modern, decent 500W PSU, and seeing where that gets you. The outlay shouldn't be that excessive, and all PSUs die eventually, while a dry-stored unit usually suffers little degradation over the years. You could also resell it to someone looking to build a new machine, if it really isn't the PSU.