Computer won't switch on

[DrKaufman]

Hi,

I just finished building my first computer system, but I've run into a problem. When I plug the computer in and press the power switch on the front of the case, everything turns on for a split second then switches off. The power LED on the mother board is on, the computer just won't switch on it seems. I've tried a few things already based on the advice of a friend, like plugging the fans directly into the power supply, plugging 20 pins into the main connector instead of all 24 (I've tried 24 initially), I've even re-wired it 3 times. Could someone please help me with this? Did I wire something wrong or connect it to the wrong place?

Thanks in advance

EDIT: I'll list my components if it is any help

Asus A8N5X Socket 939 Motherboard
AMD Athlon 64 3200+ Venice Core
A Data DDR 400mhz 1024 MB Ram
Sapphire Radeon X1600 Pro
Xion 400 Watt PSU with 20+4 main connector
2 X Masscool 80 MM fans
Onboard sound
Onboard LAN
Seagate 160 GB SATA HD
Sony DVD Drive

[capequahog]

is the pwr spply sw on 115 in the back, unless your in a 220 country, do you have a spare pwr spply, could be many diffrnt things i guess, compatible ram, etc, someone 'll find it here

[capequahog]

the reset and pwr leads arnt switched from the front?? yada yada

[DrKaufman]

No, the reset and power button cords are plugged into the right places, I'm sure of that. As far as I know the ram's compatible, and I'm usin 115 V.

[Whyzman]

Welcome tohttp://www.pcguide.com/ubb/pcgubb.gif Forums!

Due to the propensity for problems booting up a new system, it works well to start with as few components connected as possible. Troubleshooting is much easier with fewer variables.

I would suggest disconnecting everything except for the motherboard, processor/sink/fan assembly, one stick of RAM, keyboard, and monitor. Placing the motherboard outside of the case on a piece of cardboard works well to eliminate the possiblity of a dead short to the case.

Press start and see if you can make it through POST...

Also, make sure that the heatsink fan is connected to the appropriate motherboard header. Some motherboards won't continue the boot process unless RPMs from the fan are detected to protect the CPU.

[Whyzman]

I usually use Memtest 86 through a floppy dirve if all is well after adding all the RAM sticks. I then add the harddrive and use the manufacturer's diagnostics to check the integrity of the drive. These are also on floppy and like Memtest, they are self booting...

Then, add one component at a time. If you run into a glitch the last component is usually the culprit. Also, be sure that all the stand-offs are where they should be...extras not aligning with a motherboard screw should be removed...

[jlreich]

Sorry I don't have much time right now so this will be quick.

Did you plug in the 4pin power connector (not the 4pin part of the main power connector).

Is the CPU fan connected to the motherboard?

[DrKaufman]

Yeah, hang on I'm testing Whyzman's first idea. I don't have a floppy drive though :(

[Whyzman]

Floppy is a good thing to consider...there are some really decent programs, including diagnostics, that can be quite useful before Windows can get in the way... :) Plus, a floppy is dirt cheap these days...or, you can scrounge one from an older system not in use...

[DrKaufman]

Well I tried your first idea and it still refused to power up, but I couldnt connect a monitor or keyboard (long story), and I had the motherboard rest on the metal siding on the case because the power cables were too short to take it out of the case. This time though, I didnt even get a response from it as opposed to a split second whir of the fans. Did the lack of a keyboard/monitor and the position of the mobo affect anything?

I'll scrounge a floppy drive from a system I got way back from 95', back when Windows 95 was cutting edge. Heh. :p

[Whyzman]

Best to put a piece of cardboard between the metal case and the motherboard. If the connections are a bit length challenged, you can disconnect and use a flat blade screwdriver to contact the power pins. The power switch is a momentary switch so it is only necessary to make brief contact. The speaker is the only important item to keep connected...even if you need to remove it from the case.

If it is shutting down immediately after pressing the power button, you might want to have a look at the CPU/sink interface. If you used the stock heatsink, did you remove the protective plastic often covering the thermal pad?

[DrKaufman]

Just came back from work and I'll give it another go. I checked the heatsink and I did remove the plastic piece. This may sound like a dumb question, but which cables are the speaker cables? I don't think I hooked those up...in the meantime, I'm going to see if I can get the mobo out of the case. I may just be able to get it out while still within range of the cables. As for the speaker cables, do you have to have those in for the system to boot?

[Whyzman]

No, not to boot. However, the BIOS uses beep codes to tell us the POST (power on self test) progress. The speaker should hook up to the same header as the power, power LED, restart, and HDD LED.

Some of the newer motherboards might have a diezo speaker built-in to the motherboard...in which case, the external speaker connection would be moot. You might want to check your motherboard manual for clarification.

[capequahog]

i just did a new build and everything works fine but i never had any beeps at any point and still dont on start up, audio on everything is ok, no case spkr involved, mobo=MSI K8N Neo4 Plat 939skt

[capequahog]

i wonder if theres a bios enable for the beeps on mine, sorry not trying to hijk thread

[Whyzman]

I'm not quite sure if your above statement is to be followed by a question mark, or if you're pointing out you find that the POST codes are unnecessary?

You might be one, like Budfred, who's recent attempt to boot his new system ran into problems. Upon inspection, the case did not come with a speaker which would have helped with pinpointing how far in the POST process he was able to get. POST codes can tell us if the RAM is a problem, or video, etc., all which happen before any images make to the monitor...

[Whyzman]

You may have a newer board that has a built-in diezo speaker and are just not aware that at the end of a successful POST you will hear one beep. Or, you have one of the cases without a speaker. Budfred's manufacturer told him that they no longer included speakers because "all" new motherboards did not need them...

http://www.pcguide.com/vb/showthread.php?t=44070

[DrKaufman]

Hey, I just got it working! Turns out that a few of the spacers under my mobo rattled out of place (must not have tightened them enough) and caused the mobo to touch the bare metal on the case. Anyway, thanks for all the help you gave me, you made a genuine effort and I really appreciate it. Thanks again.

[Whyzman]

Hehe...yep, that's why we go for the barebones boot outside of the case...eliminates the possibility that the board is shorting to the case...usually having to do with misplaced stand-offs, or screws holding the board pinching the copper traces...also effectively shorting it out.