IMPORTANT

The problem turned out to be that the CMOS battery was exhausted, so changing it was enough. Make this test as the first test on the motherboard, because you could give for dead the whole mobo just because of the battery!

Original question

So suddenly, overnight, my computer doesn't turn on anymore: not a single sound or light when I hit the power button.

This is the system:

• psu: Cooler Master V850
• case: anidees AI-CL-Cube-W-RGB Cubo Case
• mobo: Gigabyte X399 AORUS Gaming 7
• cpu: AMD Ryzen Threadripper 1950 X 3.4GHz 32MB L3
• ram: Corsair Vengeance RGB LED 32 GB, 2 x 16 GB, DDR4 2666 MHz C16 XMP 2.0
• vga: Gigabyte AORUS GeForce GTX 1070Ti 8G

(I have omitted other components, like the HD, as it being broken is not compatible with a no-sound-nor-light-anywhere, as far as I know; but if more info is needed, please, let me know.)

My first thought was the PSU, so I tried the paper clip test, and I hear the fan noise from the PSU. Is this test enough to assume that the PSU is working, or at least that the whole system should give a minimal sign of life?

If the answer to the above question is yes, then my understanding is that it could be a mobo failure and or something wrong with the power button of the case, the reason being that since cpu ram and vga are connected to the mobo, my understanding is that if the mobo was ok, I should at least see some light on it, for instance the one telling me the OS is not standing yet.

So how can I make sure the power button is ok, and, if it is, that the mobo is totally dead?

In hindsight, is it possible that brownouts and "the opposite of brownouts" can break a mobo? I thought that they mostly kill the PSU, which I way cheaper than my mobo :(

2

2 Answers

While brownouts (loss of power) are not likely to damage your computer, power surges when the power comes back on, definitely can. Electrical devices that you do not want damaged from surges should be plugged into a surge protector, at minimum. PSUs generally have fuses in them, but they are not a guarantee that your computer will be safe.

The first step you need to do is check if your power supply unit is functioning properly. The "paperclip test" is not a useful test. All it does is show that PSU will turn on, nothing more. While knowing it will turn is good, it doesnt tell you if the PSU itself is damaged and outputting the wrong voltages, which can destroy your computer. These voltages can be read with a multimeter. However, based on your post, I gather you lack knowledge in electronics. I would suggest purchasing an ATX power supply tester. You do not need a fancy or expensive one. This will tell you if the PSU will turn on and far more importantly, if it is outputting the proper voltages.

Once you know your PSU is working properly, then you can move on to troubleshooting other issues.

6

Gigabyte tech support solved my issue, which was: the CMOS battery was probably exhausted, or close to that.

This is the main part of their message:

Please try a full reset of the motherboard:

• Switch off power supply and wait 30 s
• Remove CMOS battery.
• Short-circuit the contacts in the battery holder for about 2s.
• Remove short-circuit.
• Reinstall CMOS battery.
• Now short-circuit Clear CMOS jumper for 10 s.
• Remove short-circuit.
• Turn on the PSU switch.
• Start system and immediately boot into the bios setup.

I will now accept my own answer, because, in hindsight, anybody with good hardware experience (unlike me), upon reading the title PC does not boot (no sound, no light, nothing) should be able to make the hypothesis that the CMOS battery (which I didn't even know what it is) is exhausted, along with other hypothesis

3

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