PC turns off under load

[Amongalen]

The problem started few months ago but its getting worse and worse. Sometimes when I play some games my PC just turns off. I've tried to fix it myself, done some testing. It turned out that when I decreased GPUs overclocking it worked fine for a while. However, problem returned after some time. I've restored GPUs overclocking values to defaults and it worked fine for a while again. Now I got the problem again.
I've done some testing. Running Prime95 - everythings fine. Running furmark - PC turns off instantly! My friend told me that it might be RAMs and I should switch their positions. Tried it, same problem. Don't think its GPU overheating as PC just turns off instantly when trying furmark, there is no time for it to overheat.
When I set core voltage and power limit to minimum in MSI afterburner I can run furmark but I don't think its the way of fixing this problem, it might return again.
What could cause such problems? My guess is its faulty PSU but i'm not sure. Do you think 550W PSU is enough for my setup or I should buy more powerful one?

My setup is as below:

• 
  ■Intel Core i5-4690K, 3.5GHz, 6MB, BOX (BX80646I54690K)
  ■ MSI Radeon R9 390 8GB GDDR5 (512 bit) HDMI, 2x DVI, DP (R9 390 GAMING 8G)
  ■MSI Z97S SLI KRAIT EDITION, Z97S, 1150, DDR3, SATA3, SLI, (Z97S SLI KRAIT EDITION)
  ■XFX Black Edition XTR 550W Fully Modular 135mm 80+ Gold (P1-550B-BEFX)
  ■G.Skill DDR3 16GB (8GBx2) 2400MHz, CL11, SNIPER Dual (F3-2400C11D-16GSR)
  ■Toshiba P300 Performance 3.5 1TB
  ■SSD Samsung 850 EVO 250GB SATA3 (MZ-75E250B/EU)
  ■Monitor Dell P2214H
  ■CPU SilentiumPC Grandis XE1236 (SPC099) - CPU cooler
  

 

[Wayfall]

Do you get a BIOS screen pop up when you post and it says what caused the switch off? I have had a BIOS message show up in the past after my EVGA saved my PC from a surge (turned my pc off with a click) as a storm had caused a power drop in my area (UK, Manchester).

Do you have any spare parts so we can switch some stuff out to test components.

I'm guessing PSU but if it was you should get a BIOS screen saying the pc shut down unexpectedly.

 

[dragonoar]

I think it's your "weakening" PSU. Try using the intel HD , your PC won't turn off.
I've had the same problem (with a CX600) - insta crash with furmark, display driver crash when gaming...
Then I replaced my PSU and the problem went away.

 

[Rookie_MIB]

Agreed with a dying PSU. As a PSU gets old, the capacitors tend to dry out which changes quite a few things on how a PSU runs. Eventually it'll just die. Best to replace it now while it still works. With your setup, I'd recommend a slightly higher PSU (and a high quality unit) - in the 650w range. That would give you plenty of power for overclocking.

 

[SkyNetRising]

Not dying PSU. It's just not suitable for that graphics card.
Recommended PSU wattage for MSI R9 390 is 750W.
https://www.msi.com/Graphics-card/R9-390-GAMING-8G.html#hero-specification

 

[Amongalen]

Do you get a BIOS screen pop up when you post and it says what caused the switch off? I have had a BIOS message show up in the past after my EVGA saved my PC from a surge (turned my pc off with a click) as a storm had caused a power drop in my area (UK, Manchester).

Do you have any spare parts so we can switch some stuff out to test components.

I'm guessing PSU but if it was you should get a BIOS screen saying the pc shut down unexpectedly.

I don't get any BIOS screen pop up. I've checked system logs and it said "unexpected shut down" tho.
However, sometimes when I turn my PC after such crash I get BSoD with BAD_SYSTEM_CONFIG_INFO code. Then it restarts just fine. Not sure if its connected to this issue or any important at all.

Sadly haven't any spare part for testing.

One more thing, forgot to mention it at the first post. Its not like my PC turns off completely. My display goes black, sound goes off, no input (probably). However, power light is on and fans are running.

Not dying PSU. It's just not suitable for that graphics card.
Recommended PSU wattage for MSI R9 390 is 750W.
https://www.msi.com/Graphics-card/R9-390-GAMING-8G.html#hero-specification

It was running just fine with my 550W for about half of a year, overclocked.

Ohh, and when I calculated total wattage needed for my setup in some online calculator it said its 480W or something like that

 

[dragonoar]

Not dying PSU. It's just not suitable for that graphics card.
Recommended PSU wattage for MSI R9 390 is 750W.
https://www.msi.com/Graphics-card/R9-390-GAMING-8G.html#hero-specification

What do you mean by "not suitable" ?
If the power supply was not enough it would simply not be able to run games from the start. OP said the problem started few months ago.

 

[dragonoar]

Try using the integrated graphics, OP.
That way you can be sure that it's the PSU that causes the problem.