Computer won't start

Clarifications

When asking a question a second time, it would be a good idea to post a link to the old question.

http://tinyurl.com/c3jdw9

At this point, the first thing I would do would be to remove all the screws that hold the motherboard to the case.
Then, either set the motherboard on the bench, or insulate it from the case and see what happens when you attempt to power it up.

If it now powers up, you need to inspect the case. Either a standoff is too large in diameter, or in the wrong place and is shorting out part of the motherboard.

If you care to post details about the hardware such as make and model of everything, we can make some more specific suggestions.

Another thing to check is that you have ALL of the power connections plugged in. This includes the full 20 or 24 pins for the power supply and the 12 volt power connection.

Make sure that none of the front panel wires are shorted to the case or shorted out.

I have had some strange boot problems with a couple of motherboards that did not properly detect the installed CPU. I continually had to reset the CMOS memory until I was able to configure bus and clock settings that were compatible for both the CPU and the motherboard.

Still, your problem sounds like an extra connection somewhere. Be it a misplaced standoff, or a miswire to the front panel, there almost has to be an extra connection somewhere.

One last thing, even though you should get POST beeps for this, check that you have the correct type and speed RAM for the CPU. Perhaps the RAM does not support the FSB speed required for the CPU.

Chas

1. What make & model of Motherboard?
2. What make & model processor?
3. What make and model power supply?
4. lastly... what make and type and amount of RAM?

That information would provide a clearer picture of the setup.

standoffs, if you are replace them with nylon standoffs if you can't, dont over tighten the screws. It could also be that the controller cards on the drives have gone. Do the drives work in another System.

Do as TheChas has suggested by doing the bench test and add one hard drive at a time.

And then see if it will start now.

If it does the PS you have fitted is faulty replace it with one that works. :)

If unplugging the Mains has no effect do as The Chas suggested and lift the M'Board from the case.

Col

Check every thing that he said to. But a new question, is this a computer that you have been using and it is now giving you problems? Or have you upgraded to a new system?
Have you bought a new, computer, main board?
If so you need to read the doc's for it and do what it tells you to do.

I once had a machine that the power supply and motherboard blew out at the same time..or because of one another. Anyway, I replaced the parts and the machine would not go. Long story short; I cleaned off the old compound from the CPU & heatsink and added new and sure enough. Apparently, the old compound fails to make a seal with the heatsink alowing the CPU to heat up in a short time. Hope this helps.

Okay the fact that you are getting a boot of the mobo with no accessories attached shows that the mobo is at least partially functional, as is the PSU.

However..... What is the rating of the PSU?
250, 350.... You might not have enough output from the PSU when everything is plugged in.

Then again I could be wrong..