Computer crashes on any output but VGA...

Hi guys.

I need some help, I'm running out of ideas.

Some time ago, actually some years ago, I got a new monitor from my nephew, as a present. Nothing extrordinary, a Hanspree 23". It has worked well enough, allthough I experienced that when using its HDMI input, the computer was unstable.

I wrote it of as an error in the drivers or even the monitor, and just used VGA instead, which just worked. Since then much has happened the PC has e.g. went from Win7 to Win10, but has otherwise been rock solid stable. It basically _never_ crashed.

A month or so ago I upgraded the GFX card from a XFX R7770 to a XFX RX480 RS. This brought a "problem" with it, as there was no VGA output (not even through DVI-D).
Not really a problem as I was planning on using DP on a new monitor, but for now I had to use HDMI.
This brought back the problem with instability.

Thinking it could be the monitor, and as I had planned to upgrade to Freesync anyway, I bought an AOC G2460PF. Plugged it in through DP to get the full fresync range of 35-144Hz. The monitor works well, and is a big upgrade from the Hanspree.
But sadly the computer was still unstable.

I then started to do some troubleshooting. Installed the old GFX card and the Hanspree through VGA. The computer became stable again. The same with the new monitor through VGA, solid as a rock.

With the new monitor through both HDMI and DP -> unstable. Installed the RX480, also unstable. Tried DVI-D to the new monitor, also unstable.

I started to notice a pattern though. The computer allways froze when I was away from it. I would walk away from a working computer, go to the toilet, or to the kitchen. When I returned the PC was frozen with a black screen.
Eventually I found that it happened when I turned lights on and of. Especially the flourescent light in my bathroom could crash the PC....

I'm electrically educated, so I realized this could perhaps be interference coming through the mains. Still it was mysterious, as to why it worked with VGA. But anyway, I decided to upgrade my oldish Corsair VX450 PSU, to a EVGA Supernova G2 650. The VX450 didn't have the necessary 8 pin VGA plug so had to use a converter, and it was perhaps a bit underpowered. So I was planing to upgrade anyway.
I really hoped this could fix it.

Sadly it hasn't. The computer is unstable as soon as I use a digital output to my monitor. If I use VGA, the problems disapear. But that is not a possibilty with my new GFX card, and should'nt be necessary anyway.
At least the new PSU is quiter than the old one.

I have also tried moving around power cables and signal cables to rule out interference between cables. Power and signals now run completely separate. No succes...

What on earth is wrong with my setup?
Why will it run rock solid 24/7 through VGA, but not on any kind of digital output from PC to monitor?

The rest of the PC is an old ASUS Sabertooth 990FX with an AMD FX-8150 running stock speeds. 8Gb Corsair DDR1866 ram.
Windows lives on a (soon to be replaced) Samsung 840 EVO 240 GB. There is also a Samsung Blue Ray burner, a Kingston SSD and 2 2,5" HDD's in the machine. Nothing earthshattering.

I'm at my wits end, I must say. I really can't figure this one out.

so same results with new gpu, psu and monitor? did you replace the hdmi cable?
maybe try a ups since your home wiring seems iffy. your lights should not affect the pc like that!
one other thing ive seen cause random issues is the corsair ram youre using. try bumping the voltage in the bios a bit. every single set of corsair ram I have ever used needed a voltage bump. it should be 1.5v stock try 1.6v. thats what I need for my ram to be totally stable.

HDMI cable replaced with the one that came with the new monitor, and I also tried with the one I use for my TV. With no result.

I dont think its the wiring in my house. I have another, older PC up and running to (running as a NAS), it never crashes like this.

You are absolutely right, the lights should not affect the PC at all. I work with computers for a living, and have never seen this behaviour before, anywhere. I am quite determined to find out what is causing it.

And why the difference between VGA output and other superior digital outputs?

I will try a voltage bump on the mem. It could help who knows

yeah this is a new one for me(20+ yrs exp). im totally guessing but maybe there is a power noise issue caused by the difference between the analog vga signal and the digital hdmi signal. maybe try a different power circuit for the tower if you can. just as a test, run an extension cord from another location in the house that is on a separate breaker. your bios is all up to date too?

The power noise issue is something I have been thinking about too. And the problem affects DVI-D and Displayport too, just not VGA.

I'm also considering to get an earth wire routed to the outlet where the PC is hooked up. I have never needed it on my other PC's, but some people recommend it anyway.

I have bumped the voltage to 1.625 (in the yellow zone in BIOS) on the RAM. Time will tell if it does anything.

Yes, BIOS, and every single other driver on the system is up to date. The latest BIOS for my board is rather old though.

yes definitely get the unit grounded. sorry i assumed you were in an old house in NA, where are you? to test this you can literally put a spike in the ground and run a wire through the window to the tower and screw it in to one of the psu screws. if that fixes it then you need the socket grounded.
just wanted to tick that box for the bios. 1.625 should be safe on any ram that has any type of heat spreader.

I will try to get something done about grounding it. Should be easy enough.

I am actually in a rather new building. Well new-ish, build 21 years ago.
I live in Denmark

The RAM has rather large heatspreaders, so it will be fine I think.

Thanks for all your suggestions, I really hope to get to the bottom of this. I'll try to remember updating here, when / if I find out whats causing this.

I have never heard of one like this!

Well neither have I

But this one does exist, and my hairs are getting grey because of it....

Upping the RAM voltage didn't help BTW.

I have now plugged the PSU into another outlet, to see if that makes any difference.

oh re grounding, if you have copper water pipes you can ground to those to and big appliances might be grounded too.
good luck!

Thanks.

Here in Denmark its a regulatory demand that grounding is present in some equipment (things like washing maschines or equipment that run on more than one phase).

So grounding is relatively easy to establish. I just need to install a new outlet, and run a grounding wire, to an existing outlet that has ground.

I have a couple of friends that are electricians, I will ask them to help me with it.

I'm just suggesting a way to test first before getting it wired properly. good to have electrician friends! I would def ask them for some advice since your codes are different from here(CAN).

Just an update on my progress.

I borroved a long extension cord with ground plugs and groundwire, and plugged my PC into an outlet with grounding in it.

And now it doesn't crash anymore. At least it hasn't crashed in the time its been hooked up with grounding. And I have really tried to provoke it to crash.

So it seems I had a lack of grounding