Tech input needed please

Very good troubleshooting so far.

When you did the test as indicated in your first paragraph, did you short between the green and black wires on the 20 or 24-pin connector?
Plug components back in - one at a time - to see if a component may be causing a short?

Did you test another PSU in your system?
You mentioned it but didn't see a result.
As mentioned before, a 5 volt reading doesn't mean everything is good with the PSU. A low voltage reading does mean there is a problem, then there is the intermittent faults that can drive you crazy when trouble shooting.

Do you have a voltage regulator, UPS or surge protector in line?
Power outages can effect the above items as well as your computer.

Yes Dave what confuses me is that the volts are low on test without the mobo yet rise when the mobo id connected up - it just doesn't make sense.

I think personally trying a new PSU would be the go if worst comes to the worst at least Edi will have a decent PSU to start with.

Now having said that I am just wondering if the low volts registering on the differing leads are being "supplemented" by the 24 pin via the mobo when hooked up? Again the fact that the GPU remains cool is also a two edged sword in that is it the mobo or the GPU chip being burnt out that is itself might explain why the volts because of the lack of the drain on the supply?

Jeeps this is a curly one and it would be really good to see it first hand..

edilee012 said:

Dave76 said:

Very good troubleshooting so far.

When you did the test as indicated in your first paragraph, did you short between the green and black wires on the 20 or 24-pin connector?
Plug components back in - one at a time - to see if a component may be causing a short?

Did you test another PSU in your system?
You mentioned it but didn't see a result.
As mentioned before, a 5 volt reading doesn't mean everything is good with the PSU. A low voltage reading does mean there is a problem, then there is the intermittent faults that can drive you crazy when trouble shooting.

Do you have a voltage regulator, UPS or surge protector in line?
Power outages can effect the above items as well as your computer.

Yes shorted green and a black so PSU would come on. When I ran this test I had 3 hard drives and a few case fans still plugged in got the 3.74V reading on all 5V except the standby power one. Hooked entire system back up and tested while running from back side of 24 pin connector and the 5V readings were 5.12V. I know this PSU has alot of protections on it so might be the cause for lower voltage reading when unplugged but I have no idea.

I tested another ATX PSU I have that is too low wattage to run my entire system and doesn't have the 8 pin connector for CPU power so I just tested the 20 pin connector unhooked for reference since I know that PSU works. It did read 5v where it should have and it wasn't hooked to UPS.

It is plugged into a UPS so I will test unhooked tomorrow bypassing it. The PSU is a Thermaltake Toughpower 850 in case I hadn't mentioned that.

The auction on Ebay ended today and I passed on it and good thing because it way too high that motherboard being as old as it is. I have decided to just save the cash and upgrade my motherboard, CPU, and ram to a more current system which I want to do anyways. Thank goodness it is tax time! Will run those tests tomorrow and repost...might even have another PSU in another PC that has the aux CPU power connector...just remembered it.

Good call Edi as I said earlier maybe time to look at an Intel set up mate unless you are out and out AMD. I have nothing against the latter but just find that support for Intel that bit better and I have gone over to Asus boards now after a couple of Gigabytes which good did not have such good features - although support wise they are as ordinary as Gigabyte.
Let us know how you go as you have certainly been through the hoop with this one eh?

John

Good plan, let us know your test results.

OK plugged directly into an outlet instead of the UPS and did some extensive testing so see what you think.

24 pin unhooked from mb, 8 pin cpu aux, and 6 pin vid card all unhooked and PSU paper clipped to come on. 2 DVD and 3 HDD left hooked to power. 5V plugs read 4V and as I unhook DVD and HDD's one at a time voltage increases with each drive unhook. When all are unhooked I get 5.12V. Doesn't matter which one I plug back up the voltages starts dropping, tested each one individually. Had a second cord with SATA power connectors tried it as well and same result.

Put system back together and booted into windows with everything hooked up...now here is the part I don't understand....tested from back side of 24 pin and some 4 pin molexes also and 5V plugs are all reading 5.12V!! Is this a trait of my PSU where it has to be grounded to the mb?

EDIT: Two different monitoring softwares show the 5v as 4.892v while running in windows. I think the PSU has some regulator that ramps up the volatge when load is applied...or so I have read something to this effect. If it is reading correct while system is powered then I am at the conclusion the PSU is ok. When I plugged in that spare drive for testing something must have shorted out related to the #1 PCIe slot.

If we are at an agreement on a faulty motherboard then I am going to need some some upgrade suggestions for an Intel system. I know I will be building with the I7 2700k and was looking at the Z68 boards?

Hum still think the PSU is not well as the regulators are supplied by volts above that which are supplied so that 5v should remain constant typically it is either a 7.5v 9v or 12v in line the output is "regulated" by the device. So the drop at the output has to coincide with a drop in the input.

the one in my pic is a 7805 but there 7809 7812 7815 devices and dedicated circuits that do the same job but if you look inside the PSU (BE CAREFUL) you will see these devices bolted to those large heatsinks and the 317 series are adjustable but for our purpose the regulated supply will rely much on the same principle as these devices in the the " extra" voltage is "leaked" to ground See pics

   Warning

DO NOT OPEN the PSU !!!!!

Doing so could result in you being electrocuted to DEATH.

No mate it isn't that technical to be honest just think of the middle connection being a pressure relief valve in a water pipe so that the pressure is constant at the outlet and the water is the electrical "pressure" in volts it is just diverted away to ground to keep that end voltage stable at 5v. The regulator has just a small chip in it for that purpose.

I am at a loss to explain the drop in volts though and the only thing that I can think of is that it has some compensating circuitry in the PSU to keep that voltage up when a load is a applied - in other words it could be some power saving / economy feature - but that is purely guessing.

If you lived closer mate I have shelves full of old (ish) PSU's that would get you out of trouble and you would be welcome to any one of them but.....

I had a PSU go just like yours a while ago in my tester machine and it was registering the right volts but boot and sustaining it was hopeless until a I stuck in a Coolermaster 550watt that I had hanging around and bingo the thing took off. As mentioned earlier the volts were right but the current pathetic in the original PSU that what threw me off the scent it was pure chance really as I thought the machine was dead for all intents and purposes.