Dire need of help--2 PSUs killed

1st "almost" build:
ASUS P8P67 Pro
I5 2500K (no OC)
750W Antect Earthwatts/Corsair 750WTX PSU
Radeon HD 5850 1GB card
Gskill 8GB DDR3 RAM
WD Caviar Black 500GB HD
a mullti card reader and optical drive

I say "almost" because when everything's connected and I try to power up, the PSU blows. I've ensured all connections are right. I did not put the cardboard washers on the screws to the motherboard/stand-offs as the holes have the metal rings (read that somewhere... only non-metalized holes need the washers).

After buying the 2nd PSU, I took it to a local PC shop, and verified the PSU was working out of the box. We then connected it to just the mobo (no video card, HD, optical drive, etc)... the CPU fan came on, no problems apparent. There were no POST beeps.

I go home, connect everything (still no cardboard washers), hit the legendary power button, and the SAME THING happens.

I'm lost. Obviously, the problem is on my end. Is there a way to test each component without putting another PSU at risk? What do I do?
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  1. Strange. Both are pretty good PSU's and the overcurrent detection circuits should have simply shut the PSU's down.

    ccrider183 said:

    After buying the 2nd PSU, I took it to a local PC shop, and verified the PSU was working out of the box.

    How? If something like the paperclip trick, all you are proving is that it may not be dead. You are not proving that it works.

    ccrider183 said:

    We then connected it to just the mobo (no video card, HD, optical drive, etc)... the CPU fan came on, no problems apparent. There were no POST beeps.

    If the CPU is not installed, you will not hear anything. If the CPU was installed, you should have heard a series of long beep indicating that you have no memory installed.

    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.

    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.

    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.
  2. At the PC shop, we tested the new 2nd psu with a DMM. It seemed to be fine... until I got hold of it. The first was shot. Thanks for those links. I ordered a system speaker... stupid antec case. Hopefully, that explains why I haven't heard any POST beeps. Did I mention this is my first build?

    How can I reduce the risk of frying another PSU while testing each device? Reduce the load on the PSU by testing only one device at a time (i.e. remove video card while testing hard drive... remove hard drive while testing case fans)? Reasoning: I know there's a problem; I just need to find it?
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