computer problem,
 

I have just built a computer, initially the fan and the computer seeem to be working, till I finished installing all the componets.
The problems now is that anytime I switch on the computer, it start for few second and goes off, I have detected this by the way the fun worked. The fan start for a split seconds and goes off. can you please tell me why it is doing that. The system seem to working, from,the start all this.
Joe.

It worked before you changed/added something?

What did you change/add?

What power supply and wattage do you have? Is it the same one you had before the change? How old is it?

Can you get into the BIOS screen? If so, does it show all your hardware components?

Hi,

Welcome to LQ!

If this is a new build then I would be sure to check the processor HSF (Heat sink fan) installation. Your application of compound was proper? The CPU is seated properly? Do you get beep codes? If not then POST is not entered. Your init or lack of can be caused by several things. Proper motherboard mounting? PSU sized properly for the system?

Can you check the BIOS setup for your motherboard? You may have some sort of temperature control on the fan which prevents it comming on unless needed. The initial spin up would be to check that it works OK. (Most modern fans have a rotational sensor and can tell you how fast they are running in RPM) i.e. if it didn't do the initial spin, it would flag as faulty. :) You may notice quite few posts in these forums about fan speed/noise "problems"

Does that make sense?

Play Bonny! :hattip:

I'm betting on the PSU. Can you post some specs for this build ?

If it were the RAM the fans are usually running.

Hi,

I agree that it could possibly be a PSU sizing problem. But it could also be a thermal issue caused by incorrect or poor HSF install methods.

I've seen this happen when users fail to mount the motherboard properly by not using insulators or standoffs that cause intermittent ground issues. But here the fans would run at times but fail to run continually because of power source or sensory pickup issues caused by not grounding at the proper bonding/grommets/through holes.

My money is split: either the HSF or PSU sizing or motherboard mount issue. I would recheck the mechanical issues first if the PSU is not the issue.

Root cause is probably PSU...
 

I am going to take a wild guess here. You have a high end Video card, probably requiring multiple aux power connections, or maybe a lot of hard drives.

I recently came across a similar issue. Cause was the video card drawing down the PSU (power supply unit) voltage before the voltage had stabilized. Try disconnecting peripherals one or two at a time and see if it starts. I found that immediately turning the system back on it would power and run normally. The PSU tested fine, and in fact is running in another system without issues.

There are at least a couple of fixes if the PSU is strong enough, but slow to reach needed power output, but you need to be knowledgeable about electronics to implement. However, the best thing to do is spend money on a better PSU, making sure it has enough 3.3V, 5V, and 12V power (and multiple 12V rails) for your needs taking into account CPU, Motherboard, add-on cards and peripherals.