PSU WEIRD!

[MantaBase]

Originally Posted by Tyreal

After testing out the PSU in his machine and having it not boot up, I tried it in my own computer. The computer was receiving power. I took it out and tried jump starting it (Green and black wire). It didn't start so I'm guessing it's because the powersupply requires some load on it before it can start.

The CPU power connector was connected. I'm assuming the orientation is correct because the atx connector on both the powersupply and the motherboard has a clip to hold it in. I suppose it's possible that this powersupply has it backward but that doesn't make any sense.

And this mother board did not come out of an OEM right?

You might try a different wall outlet I suppose. Or, something is wrong with the PSU or mainboard.

[Tyreal]

I'm pretty sure it didn't come out of an OEM. The computer was tried in two different wall sockets. The PSU works in my computer but not in his. The mainboard works with PSU but not with mine.

[Lead Head]

Dose the Ultra lack any rails, like the -5 that was dropped from spec?

[Reloadron]

This is a typical 24 Pin motherboard connector:


This is a typical 20 pin connector:



The motherboard worked with the 300 Watt PSU correct? It should work with the new PSU. Shorting the Green to any Black should force the PSU on. Newer PSUs do not require a load to start. However slipping a bent paper clip down into the connector with the PSU connected to the motherboard momentarily should force a start. Something should happen.

Looking back to what I mention about orientation, it is correct right? I can't see how the old PSU works with this motherboard and a known good new PSU doesn't assuming it is connected to the motherboard correctly.

On another note the -5 Volts is no longer used and has been dropped from the PSU specification. It would be a White wire. The -5 Volts has not been used on motherboards for years. Soon expect to see the -12 Volts dropped.

Ron

[Lead Head]

Yeah, I suggested to Tyreal over MSN to trying shorting green to gnd. with it plugged into the motherboard. But there could be a reason why the PSU isn't starting, and force starting it could damage the motherboard.


Also I hope they don't kill the -12v rail, how else would I run my fans at 24v

[Reloadron]

Originally Posted by Lead Head

Yeah, I suggested to Tyreal over MSN to trying shorting green to gnd. with it plugged into the motherboard. But there could be a reason why the PSU isn't starting, and force starting it could damage the motherboard.


Also I hope they don't kill the -12v rail, how else would I run my fans at 24v

Now that was good! Yeah, -12 to 12 will definately run a 24 Volt fan. . Short of looking it up, I don't think the -12 Volts afforded much current. However we should petition to leave the -12 in the spec. I am sure Intel would listen to our reasoning.

Another trick would be to leave the motherboard disconnected but connect the PSU to a drive or something (minor load) though newer PSUs aren't that fussy about a load. Then short Green to Common and see what happens. I just don't quite get it. Assuming a known good PSU the thing should work? The motherboard works with the old PSU (300 Watts). What the heck is missing here?

Ron

[polobunny]

Manisare motherboard might be more picky on the PWR_GOOD signal than Tyreal motherboard.

The old 300W PSU is closer to normal rating for PWR_GOOD signal.
The new PSU PWR_GOOD signal might be a tad off spec (or Manisare computer is just a b**** when dealing with it) so Tyreal computer still starts but Manisare computer doesn't.

That was my idea.

[Dr. V]

It could be a simple little thing like the PSU in question isn't giving a signal that the motherboard "likes". One of those odd cases of compatibility is my verdict, based on what I've seen.

Motherboards are very particular about the received signals from PSUs to actually start and power up. I'm assuming the worst; but it seems like the only explanation.

[Reloadron]

This is a point where a good DMM (Digital Multimeter) would come in handy. It would be nice to see first hand exactly what is going on when the power button on the front of the case is depressed. I would love to see that PWR_ON command and what it is doing at what levels. That is what should be getting things going. The only tool better than a DMM for looking at stuff like this would be a scope which would show a true graphic representation of what is going on.

Ron

[Dr. V]

Originally Posted by Reloadron

This is a point where a good DMM (Digital Multimeter) would come in handy. It would be nice to see first hand exactly what is going on when the power button on the front of the case is depressed. I would love to see that PWR_ON command and what it is doing at what levels. That is what should be getting things going. The only tool better than a DMM for looking at stuff like this would be a scope which would show a true graphic representation of what is going on.

Ron

+1