CPU/Mobo PC not booting, only motherboard led lights up.

B

Botul

Recruit
I am rebuilding an old PC. When trying to boot the first time the motherboard onboard power led lights up and nothing else happens.

The power supply fan doesn't start
The CPU fan doesn't start
The chassi fan doesn't start
No reaction from the screen
No reaction from the mouse
No reaction from the keyvoard

My setup is:

Motherboard: ASUS M4A785TD-V EVO, Socket-AM3

CPU: AMD Phenom II X4 945

Memory: 2 matched pairs Corsair XMS 4096MB DDR3 PC3-10666 1333MHz (9-9-9-24) (2x2048MB) (TW3X4G1333C9)

Power: 500W Seasonic nätdel, ATX, EPS12V, BTX *

Disk: Western Digital Caviar Green 1TB (IntelliPower / 64MB Cache / SATA II / NCQ)

I have done the following checks:

Tested the power supply, measuring all voltages. All values OK.

Took the mb out of PC, put it on antistatic, added power, shorted powe switch terminals to eliminate faulty frontside powerswitch.

Cleared CMOS

Turned onboard battery upside down (changing polarity, recommended by Asus) then returning to correct polarity

Removed all connections to disks and dvd

Still no effect. Only the onboard power lights lights up.

I have been building systems as a hobby for over 20 years now, but never encountered a new faulty mb.
Do I have one now?
 
As far as I can tell it could be a faulty Processor and not a motherboard as you mentioned it lights up. The easiest way to rule out is to check the Processor on a different motherboard and or the motherboard with a different AMD CPU. This will help you element the real culprit. If the Power Good Signal is not reported then your system wont power up so you will even have to check the SMPS on a different system.
 
try these easy steps:-

1.powerup with another PSU (SMPS)
2.check the CPU on another AM3 MB/or replace the CPU.

from the above setups you can reconfirm the real faulty part !

As per our infor from Asus there is no bug/problem reported on the same m/b with II x4 Cpu.
 
Most probably problem could be due to a faulty motherboard preventing SMPS initialization. You can also perform manual power on test on SMPS( Pull out 24PIN plug from MB) by shorting Green wire with Black(Ground) on 24PIN connector pinout.
 
Surely it must be the mobo. Because PSU intialization is done by motherboard only. So even if processor is not installed, PSU should power up, right ?. If i am not wrong processor or ram has nothing to do with powering up PSU.

tush said:
As far as I can tell it could be a faulty Processor and not a motherboard as you mentioned it lights up. The easiest way to rule out is to check the Processor on a different motherboard and or the motherboard with a different AMD CPU. This will help you element the real culprit. If the Power Good Signal is not reported then your system wont power up so you will even have to check the SMPS on a different system.
Click to expand...

Just if the power LED is lit up in the mobo, is it implied that mobo is working correctly ? For instance, there are gfx cards which fail to work inspite of fans spinning...
 
You mention that the power supply fan doesn't start. Doesn't that point to something fishy with the PSU ?

BTW, I had a different problem with the same motherboard - all fans would spin, and the display would come, but it would be stuck at BIOS. Solution was to make sure the 4-pin power to the mobo was properly plugged, and move the RAMs to a different slot.
 
^^^

I didn't find any other issues with the mobo. Works perfectly fine. It was an initial glitch, prob due to some component/connector being mis-seated.
 
Did you try shorting the power pins on the mobo coz this problem might occur if your cabinet power button is not working.
 
Mate
Check the following:

1) short the PSU's any one green and any one black cable and see if PSU starts
2) If PSU starts, short the power pins on the mobo (the pins where you connect Front panel power wire) and see if PSU switches off.
3) If the above are O.K, then connect the FP power wire to the appropirate pin on the mobo and press power button on cabby.

In simple terms -

1st initiating PSU directly, 2nd initiating through mobo, 3rd initiating through cabby..

Report back...
 
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