ASUS A7N8X Motherboard problem

[Glassin]

Hi everybody!

I just installed a new ASUS A7N8X mobo with a new Athlon XP2700 cpu in my chassis and when I turn it on it runs for approximately 5 seconds then shuts down. I checked the jumpers for the correct FSB speed and replaced the power supply with a new 550 watt PSU - still to no avail. I tried another cpu that I know is good and still get the same problem. There are no heat issues since it won't run long enough to get warm. I've cleared the CMOS and reset the jumper with no luck. Anybody got an idea?

Here's the rest of my specs:
WinXP Home Edition
512 Kingston ram ( 1 stick )
160 gig Maxtor HDD
Nvidia Geforce FX5200 video card

 

[micker377]

Is the CPU fan good enough? Intel CPU's slow down when they get hot, AMD CPU's shut down in 3-5 seconds if the fan isn't working right. First thing to do is go back to square one: remove the mobo and set up on a box. Hook up the PSU, CPU, memory, and video board. If it still shuts down, check the CPU fan. If this works, add things back in until the problem appears.

 

[Glassin]

I'm sorry I forgot to tell you I installed a new Cooljag heatsink/fan combo. This is an AMD Athlon XP 2700 O.E.M. Thourobred processor/ fsb333 and the mobo is an ASUS A7N8X-X
with Nvidia N-force chipset/ Phoenix D686 BIOS.

 

[micker377]

Have you tried it "outside the box"?

 

[AyyTee1]

try changing the jumpers on the motherboard to the opposite of what the manual says. asus did not update their manuals.

 

[paparazi]

Glassin "quote"
"There are no heat issues since it won't run long enough to get warm"
If the heatsink is fitted the WRONG WAY ROUND the base won't touch the CPU core squarely, SO, won't transfer the heat generated by the CPU, to the heatsink.
Overheating can occur in under 5 seconds!
The recess in the base of the heatsink must be positioned so it sits over the raised cam box on the socket otherwise it will be "propt up" ever so slightly preventing propper thermal contact.
Another possibility is that you are connecting the CPU fan to the wrong fan header (you must connect the fan to the header marked (cpu fan) motherboards have a failsafe mechanism, they shut down if an rpm (revolution) signal is not sensed on the cpu header.
Thermal paste must be applied to the CPU core (about the same volume as a couple of grains of rice.
Lastly, some newer heatsink/fan units use slow turning, 2500rpm or less, fans, some motherboards struggle to pick up an rpm signal from these low spinning units so the failsafe kicks in and shuts down (I don't think this is the case with this fairly modern Asus board)
Martin
Martin
Martin

We like members to GIVE and not just TAKE.
Participate and help others.

 

[ceh4702]

I had to reset my BIOS on my A7N8X Ultra 400 to get it to work. I think you have to actually remove the battery on this motherboard. After that it booted right up.

On some versions of this motherboard a new BIOS needs to be flashed to get it to work. You have to know what version of the motherboard you have. Should be a version number on the motherboard. I think it is between the AGP slot and the PCI slots.

If you do not like my post feel free to point out your opinion or my errors.

 

[Glassin]

Okay; the heatsink is installed the in the correct position with the fan connected to the cpu fan port and applied with thermal paste. I've even switched the heatsink/fan with an older one. I have tried switching the jumpers one at a time and restarted it with the same results but I haven't done them all at the same time. Right now I have the board hooked up outside the box and still have the same problem. I did reset the CMOS and removed the battery but still no luck.

 

[micker377]

Have you tried just motherboard, PSU, CPU, video card, keyboard - just to see if it will post?

 

[Glassin]

That's how I set it up outside the box with just the mobo, video card, PSU, and keyboard.

 

[paparazi]

Glassin
Not wishing to push the point but did you actually remove the heatsink and check where the recess is positioned.
Does the heatsink "float" as in, are you able to move the heatsink freely when mounted? slightly side to side.
Martin

We like members to GIVE and not just TAKE.
Participate and help others.

 

[ceh4702]

Did you smash or crack the CPU?

Is the fan plugged into the header for the CPU fan on the motherboard?

Do you have an older CPU you can test on that motherboard?

If you do not like my post feel free to point out your opinion or my errors.

 

[Glassin]

Hi guys
First, Martin:I know the heatsink is in the correct position because I've put 3 different heatsinks on this board whle trying to fire it up and each one that I've removed had left the impression of the center of the cpu in the thermal paste. They all have a camphored area on the base that I know goes to the front of the socket ( where it has "Socket A" imprinted).
ceh4702: the processor and the motherboard are both brand new straight out of the boxes with absolutely no visible damage. I'm thinking that it's the motherboard since I did try a processor that I know is good and it did the same thing ( not POST; cut off after 5 seconds ).

 

[henrymalega]

You know..I had A similar query regarding an Asus mobo. You guys were rather helpful. Especially the tip to set the jumpers opposite of what the manual said. I have an Asus a7a266 with a amd 950 with 512 megs of ram. Same thing. start up, then die a few seconds into boot. I set everything back to default settings and booted from a cd with a hard drive already set up with win2000 on it. She flies around the room now. I hope my input is helpful..