PC randomly shuts down at boot

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venge86

venge86

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Sep 21, 2015
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This is quite a strange issue I'm facing. I've got a PC, custom build:
i7 4790k no OC, cooled by hyper 212 evo
Dual 2x RAM G.SKILL 1866Mhz 8GB
ASUS Z97-PRO GAMER
ASUS Strix 970 GTX OC
Corsair VS550 PSU.
Windows 10

This PC works fine. I've played the most demanding games for HOURS. Like 6-7 hours straight of GPU @ 99%, cpu @ 50%. I also measured the PSU voltage, and it's on spot 11.996V on extreme load (like 90% cpu & 99% gpu).
But the problem is: sometimes, I boot my PC and just before the loading windows circle appears (just before USBs get their power), it shuts down. It doesn't go off completely, just the mobo goes to standby (970gtx still has its power led on). Then I press again the power button, and it simply opens without a problem, everytime (it's not the power button btw, i checked it). Now it's pretty frustrating since it happens... maybe once in a week... Today it happened twice. But tomorrow it might not happen at all, even if I reboot it 10 times in a row.

It NEVER EVER did shut down when playing or surfing or whatever doing in the PC. My PC has stayed open for 1-2 days straight without a problem.
It's so strange because it's not always happening...

Any ideas?
 
Solution
Dark Lord of Tech
It's also not Haswell compatible.

Corsair states:

When an Intel Core (i3, i5, i7) processor is idle, it goes into a sleep state that requires less power than when the CPU is active. Since the motherboard voltage regulation modules that provide power to the CPU gets their power from the power supply's +12V rail, these sleep states can dramatically reduce the load on the power supply's +12V rail.

According to Intel's presentation at IDF, the new Haswell processors enter a sleep state called C7 that can drop processor power usage as low as 0.05A. Even if the sleeping CPU is the only load on the +12V rail, most power supplies can handle a load this low. The potential problem comes up when there is still a substantial load on the power...
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venge86

venge86

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Sep 21, 2015
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Since it's our weak link, shouldn't it shut down while doing more demanding things? Like playing? I mean, it seriously worked flawlessly... Played Far Cry 4 100% progress, Watch Dogs, AC unity, CS:GO like more than 600 hours, Max Payne 3, The new Need for Speed (awesome graphics). All these at full settings. I definitely count 700-800 hours of gametime without it not only rebooting, but without ANY flaw (like artifacts or stuff). I think can safely say it's stable.
 
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Dark Lord of Tech

Dark Lord of Tech

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Aug 18, 2009
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It's also not Haswell compatible.

Corsair states:

When an Intel Core (i3, i5, i7) processor is idle, it goes into a sleep state that requires less power than when the CPU is active. Since the motherboard voltage regulation modules that provide power to the CPU gets their power from the power supply's +12V rail, these sleep states can dramatically reduce the load on the power supply's +12V rail.

According to Intel's presentation at IDF, the new Haswell processors enter a sleep state called C7 that can drop processor power usage as low as 0.05A. Even if the sleeping CPU is the only load on the +12V rail, most power supplies can handle a load this low. The potential problem comes up when there is still a substantial load on the power supply's non-primary rails (the +3.3V and +5V). If the load on these non-primary rails are above a certain threshold (which varies by PSU), the +12V can go out of spec (voltages greater than +12.6V). If the +12V is out of spec when the motherboard comes out of the sleep state, the PSU's protection may prevent the PSU from running and will cause the power supply to "latch off". This will require the user to cycle the power on their power supply using the power switch on the back of the unit.

While we are still working with Intel on the details of the testing methodology they use to check PSUs for Haswell compatibility, it is already known that a power supply that uses DC to DC for the non-primary rails (the +3.3V and +5V) will not have an issue with the new low power sleep states. This is because a DC to DC buck converter is used to convert +12V to +3.3V and +5V. This means that no matter what load the CPU puts on the power supply, there will always be a load on the +12V because the +12V is required to provide power to +3.3V and +5V.

Corsair utilizes this DC to DC technology in most of their power supplies. Starting with the CX750 and CX750M and moving all of the way through the GS Series, TX and TX-M Series, the HX Series, both the AX Series Gold and AX Series Platinum, and the new AXi Series. So whatever your budget, if you choose Intel's new Haswell processor and wish to utilize the new, low power C7 sleep state.

Not saying it's the issue , but you should have a quality PSU running good components.
 
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Solution
venge86

venge86

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Sep 21, 2015
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aw... I knew it wasn't compatible, but I read this stuff now: If the +12V is out of spec when the motherboard comes out of the sleep state, the PSU's protection may prevent the PSU from running and will cause the power supply to "latch off". This will require the user to cycle the power on their power supply using the power switch on the back of the unit." . Damn, I think you might be right, this PC deserves a much more decent PSU. But if I buy a new one with $120+ and it still happens, well, it won't be good ^_^. Anyway I marked it solved because it's the only thing that makes perfect sense. I'll buy a PSU and post here later for details. Cheers.
 
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venge86

venge86

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Sep 21, 2015
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They are quite decent, and good looking too. To be honest this PSU was not intended for this machine. I sold an fx- 8350 and an asus mobo and kept the PSU, thought it might work in the end. No luck :) . I'll check the Tier list on TH and find a good one, maybe tier 2 will be ok.
 
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