New PC not powering up

November 22, 2010 at 20:09:15
Specs: Windows do
New motherboard (ASRock Core 2 Duo), processor (dual core pentium), and powersupply. Stripped it down so that nothing is on the board but the psu, speaker, and the on button. Testing seems to show that the power supply and on button are working fine. When all 24 pins are plugged into the board (20+4) the psu gives a single click, then nothing more. It can be repeated only when unplugged, replugged, and the power button pushed again. The 5 volt red line on the 4 pin connector twitches when the button is pushed. No beeps. With only the 20 pin connector plugged in the cpu fan will come on for a few seconds, then shuts down. This can be repeated without unplugging the psu. The board seems to be properly installed in the case with brass stand offs. Doesn't seem to be touching anything. The processor seems to be seated correctly.

Is there enough information to make a guess on what's wrong? I can return both the board and processor for replacement.


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#1
November 22, 2010 at 21:05:54
So you tried booting up without any RAM installed? What are the specs on the psu ? You should have tested outside the case first.

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#2
November 23, 2010 at 05:11:03
Intel Pentium Dual-Core E6500 Wolfdale 2.93GHz 2MB L2 Cache LGA 775 65W Dual-Core Processor. Right, no RAM installed.

Thanks


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#3
November 23, 2010 at 05:30:13
are you trying to boot your system without ram in it cos if you are that is most probly your problem do any beeps cum on when you switch it on ?? if their is a long continuos beeeeeeeeeeeeeep that means your mobo is blown .
if your system still does not turn on with ram in it try reseting the bios by taking out the battery for 5 seconds then put it back in our system

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#4
November 23, 2010 at 05:36:16
You should have benchtested the board before installing in the case. Without RAM, the PC speaker should be beeping like mad. You mentioned the 20+4-pin plug, what about the additional 4-pin plug that powers the CPU?

We need to know the model number of your board (it's NOT Core 2 Duo) & the make/model of youe power supply.

http://www.asrock.com/mb/index.asp

Here's how to benchtest:

http://www.techsupportforum.com/har...


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#5
November 23, 2010 at 08:09:19
"We need to know the model number of your board (it's NOT Core 2 Duo) & the make/model of youe power supply."

Whoops. Sorry, yes, that's a 4CoreDual-SATA2. Power supply is the Cooler Master GX Series 750W ATX Power Supply RS750-ACAAE3-US. The psu will power another pc just fine. An older psu that was working previously also fails to get a response from the new motherboard.

My understanding of board power plugs is that the board will most often have a 24 pin plug, or a 20 pin plug + a 4 pin plug elsewhere on the board. Apparently there are rare boards with a 24 pin plug, and then an additional 4 pin plug, but that's not the case here. If the 4 pin plug is specifically for the processor could the additional response without the 4 pin plug be indicating a problem with the processor? There are other 4 pin plugs on the power supply. Should I try substituting one of those?

"Without RAM, the PC speaker should be beeping like mad."
When both the 20 and 4 pin plugs are in there is no response outside of the slight click from the powersupply and (oddly it seems to me) the 4 pin plug 5 volt wire twitching. It's like a frog muscle being zapped with a current. Nothing turns on. My understanding/guess is that the power on logic circuit at pin 15 is not pulling up the voltage.

So far there doesn't seem to be anything wrong with what I'm doing. It's looking like there's a problem with either the processor or the motherboard, and returning both for replacement will solve my problem. Is there something I'm overlooking?

I'll look at bench testing.

Thanks,
Mike


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#6
November 23, 2010 at 08:15:11
"Many fellas make the common error of trying to use the detachable four pin connector from the 20+4 motherboard connector to power the CPU this does NOT work you must use the CPU power plug"

Holy guacamole! Could this be my only problem? How the hell is one supposed to tell the difference? The plugs look the same, and the damn 4 pin plug next the the 20 was supposed to go in on the old pentium 4 motherboards!


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#7
November 23, 2010 at 09:26:56
Follow the instructions in the mboard manual - the markings on the mboard can be confusing.

"Stripped it down so that nothing is on the board but the psu, speaker, and the on button."

I assume the CPU is in it's socket ??

The cpu fan wiring connector MUST be connected to the proper cpu fan header, otherwise the mboard will probably shut off within seconds of when you first boot.
.......

The no ram installed test .

Make sure you have a speaker or speakers or the equivalent connected to the mboard so you can hear mboard beeps (see your mboard manual if you need to).
Remove the AC power to the case/power supply.
Remove all the ram. (You don't have it installed in this case)
Restore AC power.
Try to boot.
If nothing else is wrong, you will get no video but you will hear a pattern of beeps that indicate no ram is installed, or a ram problem.
E.g. for an Award bios or a bios based on one, that's often a beep of about a half second, silence for a half second, a beep of about a half second, silence for a half second, continuously.
.....

"""Many fellas make the common error of trying to use the detachable four pin connector from the 20+4 motherboard connector to power the CPU this does NOT work you must use the CPU power plug""

The PS wiring connectors and the power sockets they plug into are almost all "dummy proof" !
The only exception is the small 4 wire molex connector you normally plug into a floppy drive's or older video card's pins - that can sometimes be plugged in so it's not on the pins right.
All the connectors coming from the PS, and all the power sockets on the mboard, drives, and on modern video cards, are designed such that the plastic around the pins on the male connectors and in the female sockets, and/or the shape of the plastic on the outside of the socket, cannot be used with anything they weren't designed to be used with !
E.g. You cannot plug in the 4 pin connector in the PS's main connector 20 + 4 wiring pair into the 4 or 8 pin socket on the mboard !

You DO, however, have to have all required connectors from the PS plugged in !
You must connect wiring from the PS to the main 24 pin socket on the mboard, AND to a 4 or 8 pin socket on the mboard.
If your PS has the usual 20 pin + 4 pin pair of main plugs, if your mboard has a 24 pin main socket, you must plug in both of them - the 4 pin one is in the same wiring bundle as the 20 pin one, if it isn't already clipped onto the 20 pin one. Sometimes that 4 pin connector is tied back to the same wiring bundle so it isn't in the way of the 20 pin one.

If the mboard has an 8 pin power socket rather than a 4 pin one, if you don't have an 8 pin plug from the PS that fits in it, or a pair of 4 pin plugs in the same wiring bundle that will plug into that socket, then you must buy and use a wiring adapter for the 8 pin socket.

f you have a video card in a mboard slot, if it has a power socket, or sockets, you must connect wiring plug from the PS to that (those) socket too.
.....

.


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#8
November 23, 2010 at 09:58:34
Thanks for the reply.

The board has a 20 pin socket, and one 4 pin socket somewhat removed from the 20 pin and next to the cpu. I had assumed that the 20 + 4 plug was to go into the motherboard, as in the previous ATX motherboard I had. In online pictures the other 4 pin plug coming off the psu looks exactly the same as the 4 pin plug from the 20 +4, except that it has yellow wires instead of a red one for the 5 volt pin. Have to wait till I get home to look at my psu to be sure, but it seems that the plugs themselves are interchangable. I could be wrong. Have to wait till I get home.


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#9
November 23, 2010 at 10:07:42
"In online pictures the other 4 pin plug coming off the psu looks exactly the same as the 4 pin plug from the 20 +4"

It's NOT the same !
The plastic around the pins on the plugs and in the sockets is shaped such that you cannot plug ANY 4 pin connector into the wrong socket !
(Floppy drive power connectors on the drive, and power connectors sometimes used on older AGP cards , are pins on a header, not a socket.)

You have a 20 pin main connector socket and a 4 pin connector socket near the parallel port. Only one 4 pin connector from the PS can be plugged into that.Your PS may have a 4pin connector that fits in that socket that's by it self, or a pair of 4 pin connectors in the same wiring bundle (they may be clipped together as an 8 pin one) , one of which fits in the socket. If it has ho 4 pin connector that fits, then it's got a one piece 8 pin connector , and you must buy and use an 8 pin to 4 pin or 8 pin to two 4pin wiring adapter.


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#10
November 23, 2010 at 11:10:54
The Asrock web site displays for the board connectors:

- 20 pin ATX power connector
- 4 pin 12V power connector

So that must be it! I had the wrong 4 pin connector in there. But I swear to God that the 5 volt 4 pin has the same corners as the socket and went in just fine. No indication that it shouldn't go in there, so long as I wasn't looking at the voltages (or, I would guess before looking at it, carefully following the manual). I love it, therefore it must be right. It'll be 6 hours before I get home and I find out. Suspense is killing me.

Thanks all for allowing me to think this through.


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#11
November 23, 2010 at 12:26:36
"I had the wrong 4 pin connector in there."

How many times do I need to tell you ??

YOU CANNOT PLUG IN THE WRONG 4 PIN CONNECTOR !
IT WILL NOT PHYSICALLY PLUG IN !


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