A7N8X power up problem

L

lduong

Geek Trainee
Hello,

I am trying to put back together an old mobo and cpu (which were both functionning in January 2006). I have an A7N8X board with an athlon 2400+ CPU. I bought two different power supplies at 450W (one ASUS then Antec). When I hook up the case cables to the Power SW jumpers, impossible to turn on the computer via the power button (in both positions). I jumped the board with a screwdriver and for 2-3 seconds the case fan and the PS fan ran before turning off. The LED on the motherboard lights up green when i turn on the PS. Impossible to reproduce except for when I took out the CMOS battery for 10min, switched the jumper to reset it and put the battery back in. Then using the screwdriver to start the board, the fans ran for 2s before turning off. I also bought an Asrock K7S41GX (Socket 462) board which the guy said was for my CPU but this board has no LED to tell me if it's getting juice. The fans never start with this MB and no activity with the power button.

Is the problem the CPU? I've tried two MB, one new and one old (but was functional) and two new PSU. The CPU stayed the same but I don't see how or when it would have fried seeing as I just changed the PC in January to have something with pci-E.

I don't know if the new MB that i bought was broken or not. In any event no activity starts. Does anyone have any ideas? Is it a short circut on the board (a7n8x)? I don't know why the asrock doesn't do anything seeing as it is new.

Thanks for any help.
 
hmmm, you got a manual with the new motherboard right?, check to see if you have inserted all cabled correctly.
also, it could be your CPU, maybe even your ram, if possible, try some different ram.

also, i would suggest trying your system with only what you need to get to the initial boot diagnostic screen.

disconnect all harddrives, cd or dvd drives, any case fans, keep your case open tho, all you need connected is, motherboard, ram, graphics card psu, cpu, thats all you need.
 
The ram used in the original A7N8X was working before. Is it possible that the RAM is corrupted on this motherboard. I have had more success with the old A7N8X than the new AsRock board. I tried simply plugging in the cpu, ram, and graphics card, no hard drive.
 
ah, thats a good start then, it seems like the CPU, i would try another CPU, but maybe it could be the ram, as i forgot to put the ram back in my pc once and turned it on, all i got was beeping, all lights were on, but no monitor.

so either ram or cpu, your using the antec psu right? that should be good enough.
 
lduong said:
Hello,

I am trying to put back together an old mobo and cpu (which were both functionning in January 2006). I have an A7N8X board with an athlon 2400+ CPU. I bought two different power supplies at 450W (one ASUS then Antec). When I hook up the case cables to the Power SW jumpers, impossible to turn on the computer via the power button (in both positions). I jumped the board with a screwdriver and for 2-3 seconds the case fan and the PS fan ran before turning off. The LED on the motherboard lights up green when i turn on the PS. Impossible to reproduce except for when I took out the CMOS battery for 10min, switched the jumper to reset it and put the battery back in. Then using the screwdriver to start the board, the fans ran for 2s before turning off. I also bought an Asrock K7S41GX (Socket 462) board which the guy said was for my CPU but this board has no LED to tell me if it's getting juice. The fans never start with this MB and no activity with the power button.

Is the problem the CPU? I've tried two MB, one new and one old (but was functional) and two new PSU. The CPU stayed the same but I don't see how or when it would have fried seeing as I just changed the PC in January to have something with pci-E.

I don't know if the new MB that i bought was broken or not. In any event no activity starts. Does anyone have any ideas? Is it a short circut on the board (a7n8x)? I don't know why the asrock doesn't do anything seeing as it is new.

Thanks for any help.
Click to expand...

i had the same problem a while ago and kicked myself after worrying about it for an age, i had placed the CPU fan on the wrong way round and it was not touching the cpu properly, (it fried the cpu) it overheated and shut down after two or three seconds, the socket A fans only go on one way, i checked this with a new cpu and heat paste to see if it left a print on the fan once it was correct i cleaned the new cpu and heatsink, re pasted and fitted problem solved, (god i felt dense) i hope its as easy as this for you, overlooking the obvious is my mistake, i wont happen again. regards and good luck Jadedhills:)
 
Hello,

Ok an update on trying to narrow down the problem. The CPU fan is attached correctly. I thought perhaps the CPU was fried but I placed in another motherboard and the machine booted fine. So far it is not the motherboard, not the RAM, not the PS and not the CPU? I don't know for sure if it is not the mobo but there must be something I am missing here. It booted fine before with the ASUS A7N8X mobo. I just can't seem to get the computer to boot via the Power SW button. I will have to try another CPU in the A7N8X mobo but I am running out of ideas (and spare parts) :)
 
No it doesn't boot (A7N8X) nor the AsRock K7S41GX using the power button nor jumping with a screwdriver on the pins. But the LED on the A7N8X lights up when the PSU is attached so it appears to have power.

The CPU functions in another mobo (don't have the model) which was plugged into its case and the power button works here.

Basically I have a test showing the CPU works (via another pc's mobo). The PSU is new (Antec) and lights up the old mobo LED (A7N8X). This board had no problems before and I don't think there is anything wrong with it. I reset the CMOS on the A7N8X but the only way I got the fans to run for 2 seconds was via the pins and a screwdriver. I gave up on the ASRock b/c there is no LED to indicate if the mobo is getting power. It also does not respond to the power SW. Somehow I think it is something really simple that I'm not seeing. What are the causes of the chassis fan and PSU fan turning on for only 2s before shutting down?

I hooked the A7N8X to the PSU, the chassis fan power supply to the mobo (with the grounds correct). The CPU placed correctly in the mobo with the fan (only one possible direction). The RAM was placed in tightly as well as the graphics card. No hard drive nor cd-rom plugged in for the moment. The case power SW cable connected to the correct pins on the mobo. That should be enough to just boot into the BIOS.

I am going to test another CPU with the A7N8X but I'm sure if I hook it up the same way, I am missing something...
 
you didnt reverse the reset and pw/switch wires coming from the case?

are you using conductive thermal compound? and using it right? too much and spill over with the wrong stuff will cause a world of problems.
http://www.arcticsilver.com/arctic_silver_instructions.htm

to eliminate a short in your build, i would do is to do an out of case build, set your motherboard on a sheet of cardboard, only the essentials installed, jump the motherboard switch pins with a paperclip to start it, see if it goes.

as was mentioned before, check the orientation of all power and data cabling..
 
No I double-checked the wires from the case multiple times with 2 other persons. The power SW cable was connected and I even tried without the reset cable.

I tried and out of case build using a screwdriver to start up the machine and once it came on but the fans turned off 2 seconds later. I read that this could be due to a short circuit but why would the motherboard still light up the LED from the PSU?
 
I tested another CPU in the A7N8X board and same problem. So it appears to be a motherboard/PS problem... the motherboard starts up for a few seconds and turns off. I had the graphics card, RAM and cpu connected only. I had to start it using a screwdriver to touch the pins but it never responds when plugging the the power SW cable into the motherboard. I have an Antec 430W PS which is supposed to be compatible with most motherboards.

Is there a security on the board where something is missing and it will turn off after a few seconds of powering the fan on?
 
Ive not heard of a mobo with any security feature like that, i think some have a 'case-open' security feature that stops them powering up but i havent seen one in ages.

Have you checked that the board isnt shorting itself on the back side? my flatmates used to do that, every time you knocked it it would turn off - turned out the mobo was making contact with the case side.

You go all jumpers set right? try a bios reset purhaps?
 
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