PC won't boot: Psu or Mobo?

6th November 2007, 18:18

At the moment i have disconnected everything from the motherboard. There's only the cpu + cooler, memory and 1 fan

Now when I connect only the 20 Pin ATX cable with the Motherboard and i try to boot, the fan and the cpu fan begin to work.

However when i try to boot with the 12V connector (for the CPU) everything remains dead

jmke · 6th November 2007, 18:26

with 12V connector do you mean the 3-pin fan connector, a 4-pin E-ATX connector or 8-pin EATX connector?

If it's one of the last two, get a hold of a second test PSU, if it's the first, try another fan header?

6th November 2007, 18:30

the 12V connector in my case is the 4 pins, needed to power to cpu (according to the mobo manual)

jmke · 6th November 2007, 18:58

can you lend a PSU from a friend or nearby shop to check?

7th November 2007, 08:52

If the 4-pin connector isn't connected, does the computer boot or just sits there doing nothing ?
If you can't find a second psu, you could try measuring the voltages using a multimeter, anything between 11.4V and 12.6V on the 12V rail is acceptable.

Gamer · 7th November 2007, 13:07

What Psu and motherboard ?
We need info

25th December 2007, 03:56

There are some Gigabyte motherboard (P965) which have re-boot issues and disconnecting the 12V P4 cable seems to resolve the issue. This tuitorial on PSU connectors provides everything you need to know. Why there is a 4-pin 12V connector for additional power to the processor (known as P4 connector) and why some boards use an 8-pin 12V connector (known as EPS12V).

The photo below shows a Gigabyte board and the P4 CPU connector.

6th November 2007, 18:18	#1
Indizann Posts: n/a	PC won't boot: Psu or Mobo? At the moment i have disconnected everything from the motherboard. There's only the cpu + cooler, memory and 1 fan Now when I connect only the 20 Pin ATX cable with the Motherboard and i try to boot, the fan and the cpu fan begin to work. However when i try to boot with the 12V connector (for the CPU) everything remains dead Last edited by Indizann : 6th November 2007 at 18:56.

6th November 2007, 18:26	#2
jmke Madshrimp Join Date: May 2002 Location: 7090/Belgium Posts: 79,022	with 12V connector do you mean the 3-pin fan connector, a 4-pin E-ATX connector or 8-pin EATX connector? If it's one of the last two, get a hold of a second test PSU, if it's the first, try another fan header? __________________

6th November 2007, 18:58	#4
jmke Madshrimp Join Date: May 2002 Location: 7090/Belgium Posts: 79,022	can you lend a PSU from a friend or nearby shop to check? __________________

7th November 2007, 13:07	#6
Gamer [M] Reviewer Join Date: May 2002 Posts: 4,587	What Psu and motherboard ? We need info __________________

25th December 2007, 03:56	#7
Liquid3D Posts: n/a	There are some Gigabyte motherboard (P965) which have re-boot issues and disconnecting the 12V P4 cable seems to resolve the issue. This tuitorial on PSU connectors provides everything you need to know. Why there is a 4-pin 12V connector for additional power to the processor (known as P4 connector) and why some boards use an 8-pin 12V connector (known as EPS12V). The photo below shows a Gigabyte board and the P4 CPU connector. Last edited by Liquid3D : 25th December 2007 at 03:58.

6th November 2007, 18:30	#3
Indizann Posts: n/a	the 12V connector in my case is the 4 pins, needed to power to cpu (according to the mobo manual)

7th November 2007, 08:52	#5
wutske Posts: n/a	If the 4-pin connector isn't connected, does the computer boot or just sits there doing nothing ? If you can't find a second psu, you could try measuring the voltages using a multimeter, anything between 11.4V and 12.6V on the 12V rail is acceptable.

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