Help? black screen on first startup, fixed by power cycling; changed CPU, Mobo

[sacklunch]

Greetings, My current setup: 8350k (stock clocks) Corsair H100i GTX MSI Z370 M5 Samsung 960 Evo (boot) + 4 hdd via sata Corsair 16gb (stock clocks) Windows 10 Enterprise Corsair RM1000 (w/ corsair sleeved cables) r290x (ref. with Corsair watercooler) case: bequiet! base 900 fans: all Noctua (premium quiet)

The problem: when I power on the machine after it has sat all night my main monitor turns on but the screen is black. The fans on the PC are running (as is my NZXT Sentry 3), but nothing on screen. Holding the power button and restarting, the machine works fine.

Attempts to fix: I recently upgraded my cpu and mobo (two weeks ago) and the problem remains. I swapped in another PSU I had laying around, nothing; I swapped in different ram I had laying around, nothing.

Possible options: 1) problem with the GPU? I am running 4 monitors (using Startech display port hub for 3 monitors + my main monitor into the GPU via hdmi), but the problem was no different months back when I was running 3 monitors (without the Startech hub). 2) problem with the case? I have never heard of a case causing this problem.

Thoughts? Thanks ya'll!!

[captain]

Put on a pot of coffee. Disconnect everything, including keyboard and mouse.
Power it up. Works? Reconnect ONE thing.
Repeat.
Fails? There's your culprit.

[Leslieann]

While Captains idea is a good, simple start, even if it works, it can be a symptom of something bigger.

Sounds like a thermal problem, as in something got cold (did it sit in a very cold room or car?) and pulled away (the pins relaxed) or it could be a broken solder joint that closes when warmed up.

Try re-seating the cpu and graphics card.
If re-seating fixes it, all is well, the bad, if it doesnt, it could be a cracked solder joint inside the GPU or CPU. Oven baking can reflow it, but this is extremely risky and usually not a permanent fix.

[HotRoderX]

Have you tried removing the hub? That be my first step. Remove the hud try a single monitor. Also check to make sure the power adapters for the GPU are plugged in firmly and seated properly. Then might want to try checking the power supply's you tested with. A lot of brands specially offbrand's are hit and miss on quality.