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My computer (an ASUS P8H61-M LE/USB3 motherboard) has recently undergone some upgrades. Historic symptom: for a couple of weeks the keyboard has sometimes been non-responsive once the computer is suspended; num-lock and caps-lock lights don't respond (num-lock light on, doesn't go off; caps-lock light off, doesn't go on), keypresses don't bring the computer out of suspension. Power cycle required. Normally the machine is powered on an either operating or suspended; it's unusual for it to be turned off.

A couple of days ago the computer got an upgrade. i3 (65W TPD) swapped for an i5 (65W TPD) CPU, thermal paste applied but I can't guarantee with any skill; Gigabyte GV-N710SL-1GL (reportedly 19W TPD, no official figures found) video card installed. After upgrading, the computer would start and run. Any time the computer went into suspend mode it wouldn't come out again.

At some point a couple of externally powered USB3 HDDs were connected to the computer; when both were connected to the USB3 ports and the machine booted, the BIOS complained of an overcurrent and powered down the machine. When only one was connected via USB3 and the other by USB2 the BIOS did not complain and the machine booted.

A few days after the upgrade, the computer failed to power up. The cooling fans would spin up, then power down. This cycle would continue every ten seconds or so.

I figured it was a failed Power Supply Unit, so pulled the leads to the motherboard and replaced them with the leads from a spare PSU I had lying around: these are the numbers written on the spare PSU, who knows what relation they have to reality (they certainly don't seem to add up):

DC Input  +3.3V  +5V  +12V   -12V  +5Vsb
  Max A.    27A  29A  29.5A  0.8A   2A

+5V & 3.3V combined 200W  Total output 470W

I'm unable to read the existing installed PSU specs without pulling it from the case, but given the failure mode was identical between the two PSUs I think the spare's details are pertinent. Swapping the power supply didn't help.

Removing the Gigabyte GV-N710SL-1GL video card leads the computer to boot. The video card is functional, working when dropped into an alternative machine.

What is the root cause of the failure to boot, and why did it manifest a few days after the upgrade, rather than at the time of the upgrade? Do I need a more powerful PSU?

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  • You don't seem to understand what you're talking about. Your graphics card model as said doesn't make sense. Please confirm what it actually is.
    – headkase
    Commented May 6, 2017 at 4:33
  • @headkase, GV-N710SL-1GL as per the link
    – Josh
    Commented May 6, 2017 at 5:01
  • GeForce GT 710 - which more illuminates what it is.
    – headkase
    Commented May 6, 2017 at 7:55

1 Answer 1

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I can't give an exact reason but I think it is a motherboard driver issue.

A while ago, I had a TT usb 3 mouse that would run fine when plugged in when the computer was on, but wouldn't allow my PC to boot (it would just power cycle like you described) if I turned the PC on with it plugged in.

I fixed it with a combination of upgrading BIOS and upgrading all of my hardware drivers

Hope this gives you an avenue to investigate further.

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  • Loading drivers from asus.com/Motherboards/P8H61M_LEUSB3/HelpDesk_Download now...
    – Josh
    Commented May 6, 2017 at 8:21
  • The machine boots happily with the video card in, and if it remains happy for the next week I'll accept your answer! To think that I laughed when I first read your suggestion... Thank-you!
    – Josh
    Commented May 6, 2017 at 8:29

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