Daughters CPU keeps blowing fuses and killing network cards

doopydug · 30 Dec 2020 at 14:16

Any ideas whats likely to be the cause, guys?

Every few weeks, I need to change the fuse in her mains plug and every few months it eats a network card - either USB or PCI, makes no difference.

I am thinking either the PSU (Bitfenix 650W) or Mobo at fault - whats the most likely culprit, in your opinion?

Quartz · 30 Dec 2020 at 14:25

The mains plug fuse will be either the PSU or something else on the circuit. It is a 5A fuse, right? You're not using a 3A fuse? Remember that 650W is the maximum output of the PSU, not it's maximum input.

V F · 30 Dec 2020 at 14:30

Quartz said:
The mains plug fuse will be either the PSU or something else on the circuit. It is a 5A fuse, right? You're not using a 3A fuse? Remember that 650W is the maximum output of the PSU, not it's maximum input.

3A covers up to 700 watt.

doopydug · 30 Dec 2020 at 14:32

Yeah - its a 5A

Will quickly change out the PSU and see if that helps

Its only an I5 4460 with a 970 GFX CARD and a 1TB hard drive

Quartz said:
The mains plug fuse will be either the PSU or something else on the circuit. It is a 5A fuse, right? You're not using a 3A fuse? Remember that 650W is the maximum output of the PSU, not it's maximum input.

Tetras · 30 Dec 2020 at 14:43

I'd replace the PSU first, then I'd look to the motherboard. Though, if the PSU is faulty it may have damaged the motherboard and continue to eat things.

Quartz · 30 Dec 2020 at 14:46

V F said:
3A covers up to 700 watt.

A 650W PSU can eat more than 700W. Remember that 650W is the output, not the input. Assuming 80% efficiency, a 650W PSU can eat 650/0.8 = 813 Watts.

doopydug said:
Its only an I5 4460 with a 970 GFX CARD and a 1TB hard drive

You should be nowhere near the power limit, but changing the PSU is still a good idea. Do take the opportunity to look at the motherboard for blown capacitors.

andy_mk3 · 30 Dec 2020 at 14:56

I would go PSU. It's the only thing that can blow the fuse in the main power lead. A low voltage fault will just trip the protection in the PSU itself.

doopydug · 30 Dec 2020 at 15:22

Thanks for the help, guys - PSU now replaced - we will see how it goes, now

EsaT · 30 Dec 2020 at 23:22

Is wall outlet grounded?
If not, PC might be attempting to ground chassis through network wire and those "ground loop" currents might burn NICs.
(similar stray currents would happen if you attached TV connected also to antenna ground to PC)

henson0115 · 31 Dec 2020 at 10:35

sounds like a grounding issue to me, ive seen a network switch give minor shocks because it wasnt grounded correctly, first step is to check your wall outlet.