Question My Desktop PC will not boot ?

May 8, 2021
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I have a desktop that has been reliable for 3 years since I built it. What I do is take parts from unwanted pc and turn them into working ones. but this is a pc that I built for myself not much for gaming but for personal use. it may not have good specs but they are:
an Intel Core i5-4570
Asus Z87-C
2x 4GB G-Skill RipJawsX DDR3 1600
Gigabyte Nvidia Geforce GT 650 2GB
1x 256GB ADATA and 1x Sandisk 126GB SSDs
Zalman GVN Series 400Watt powersupply

the problem I am having as there are four indication LEDs when the motherboard does its self-check. the first light that lights up is the CPU LED then it shows the DRAM LED then the VGA LED then the desktop shuts off then repeats. The motherboard doesn't even try to show a boot LED at all and there is no BIOS beeps which could indicate there is not enough power getting to the motherboard. It's like it tries to boot but it stops at the VGA check. the standby LED is let up as green and the four wires the gray and purple wires show 5.00 volts and the green and blue wires show 5.10 volts so it's normal.

so I have done the following troubleshooting which are:
turned on the pc with nothing but the power supply, CPU and one stick of ram tried the different ram in all different slots
tried different CPUs
Tried different GPUs
I have changed the CMOS battery
tried to reset the Bios
turned on the desktop without the SSDs installed
I have reseated the CPU 3 times
I have looked for bent pins on the socket and they look good
I have cleaned the pads on the CPU
I have replaced the rear case fan

so I'm out of ideas but I have my suspension and have narrowed it down to 3 things which are:
the BIOS is corrupted
the power supply is faulty
or the motherboard is toast

but I have come to Tom'sHardware to get some idea what is as I don't want to say buy a power supply and ends up not being the problem. so I need some help any ideas will be some help.
 

lvt

Commendable
Apr 19, 2021
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May 8, 2021
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Is the Bios removable?



Use a PSU tester to make sure that all the voltages are OK, every PC builder should have one. Otherwise you can test the PSU on another motherboard (more tedious).



Possibly, most of the times it's about a bad capacitor or a broken resistor.
I have tested all voltages and seem fine and I just recently tryed the power supply on a two different motherboards and worked fine and yes the bios is removable
 
May 8, 2021
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Good news is that the Asus Z87-C Bios is replaceable.

Just in case you need it, you know that it's can be had for around $13.
I know there are replacements and isnt that USD I'm In NZ so it would be $17 but I still not sure if it is the bios and also how it got corrupted in the first place. As there could be a hardware problem on the motherboard that's corrupting the bios or is pro venting the bios from initialising.
 

lvt

Commendable
Apr 19, 2021
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I know there are replacements and isnt that USD I'm In NZ so it would be $17 but I still not sure if it is the bios and also how it got corrupted in the first place. As there could be a hardware problem on the motherboard that's corrupting the bios or is pro venting the bios from initialising.
Of course the Bios thing is last resort, there are many parts on the motherboard that can go wrong.
 

lvt

Commendable
Apr 19, 2021
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The question is what caused it to fail and what failed
Isn't that the same thing ☺

There are thousand of parts on a motherboard, it's very difficult to identify the source of problem without professional equipment. Even if you have the equipment and can find out the cause, most of the times it's not repairable or not worth it.

Sometimes the cause is as simple as a motherboard being bent after a couple of CPU changes. You remove the CPU, put it back and everything works fine again for the next month, then one day it won't start.
 

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