Sign in with
Sign up | Sign in
Your question

New PC build, won't power on, but PSU works..

Last response: in Systems
Share
May 29, 2011 2:53:19 PM

I just got and assembled the following parts, but can't get any life out of the PC yet when I try to power-on:

Asgard II Case
Biostar H61mh mobo
ocz modxstream 500w PSU
i5 2400
oczvertex 2 60gb
crucial ballistix 2x2gb d3 1333 ram


I have another PC that I've tested the PSU with, and it was able to successfully boot up so I know the PSU is working.

I also tried hooking up the PSU from the other PC to this one but that didn't make a difference.

When I press the power button on the case I hear no fans, no electricity, no signs of activity.

I've tried unplugging everything and replugging in, basically taken everything out and then put it back to check if there were any loose connections, but still nothing.

Any suggestions what I can do to figure out where the problem is? Thank youu!

More about : build power psu works

May 29, 2011 3:14:48 PM

Make sure you have the correct connections for the case buttons/lights on your motherboard. Depending on the case and/or motherboard this can sometimes be confusing to know which connection goes where.

If you are certain that is correct double check all connections, unplug and reinsert in case something wasn't all the way in (did that myself once with a hard drive) and try again. It could be a dead motherboard if the PSU is definitely working and your connections are all good, but bad connections is a common mistake we all do.
m
0
l
May 29, 2011 3:25:51 PM

Thanks for the answer, aaron. I've unplugged and reconnected everything a few times, since that's what I would think the problem is too. What would be a way to test if the mobo is dead? Use all my components from my other PC (theyre all compatible since the 2 PCs are almost identical) and see if I get power?

I'm wondering what the chances are of something not being compatible VS. one of the components being faulty. Are DOA motherboards a common occurrence?
m
0
l
a c 122 B Homebuilt system
May 30, 2011 4:03:59 AM

Work systematically through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.
The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
m
0
l
!