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Strange Power Supply Issue

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April 20, 2011 12:02:45 PM

I have an HP Pavilion Elite E9290f

Am am on an upgrading spree. I bought a new power supply last month and it didnt work. I returned it suspecting DOA. I got a new PSU the other day and hooked it up and the exact same problem happened. This led me to believe it is not the power supply causing the problem. I tested my theory by hooking the power supply up on a different computer and what do you know it worked.

My old power supply is a 460W and this one is a 850W. When I hook it up and press the power the computer acts like it is going to power on for .5 seconds but shuts its self off like it is a safety feature. I dont get whats wrong because the old power supply works just fine. I have tried everything I can think of and no matter what I do the computer will get power the fans will spin for a second and immediately shut off.

What could be causing this? I have verified the pins are correct.

The only possible thing I can think of is that the 4 extra pins on the 24pin mobo connector is bad. This is because when I tested it on another system it had a 20 pin mobo connection not 24 and it worked but could I really have got two different PSUs in a row with bad 21-24th pins?

I really dont think it is the power supply I think my motherboard is just rejecting it for some reason. I am getting a new motherboard soon anyways but I would like to get this fixed.
a b ) Power supply
April 20, 2011 3:07:08 PM

Does the HP Pavilion Elite E9290f use a standard ATX PSU or one that's customized for HP? To determine if the 4-pin is the issue, don't use it. Unless you added a lot of components, the PC should power up with or without the additional 4-pin connector.
April 20, 2011 6:20:57 PM

I have tried using it with only the 20 pins and it still would not power up. I know the power supply works because it works on other computers. I am not 100% positive the current power supply is standard ATX but I know the board is microATX so I would think an ATX power supply would work. I will look at the labels on the old power supply when I get home but I am pretty sure its a standard ATX power supply.

When comparing the two PSUs the connections look identical.
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a b ) Power supply
April 20, 2011 8:04:24 PM

When replacing the PSU, you didn't forget to connect the CPU power cable?
April 20, 2011 8:48:31 PM

No...and it shouldn't matter anyway the motherboard will power up without the CPU power. It just wont be able to do anything. My motherboard will no even power.
a c 144 ) Power supply
April 20, 2011 9:01:05 PM

Without CPU power, how will you know if the motherboard powers up?

Time for some troubleshooting instead of randomly replacing parts.

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%. If you have a white wire (many modern PSU's do not), it should be -5 volts.

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.

Best solution

a b ) Power supply
April 21, 2011 12:24:30 AM
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I may be wrong, but I believe the OP's system powers up with the hp PSU. If everything is connected properly, then hp probably require a PSU having specific characteristics that are not available in the new 850W unit.

Edit: A search on Google seems to indicate that this issue occurs with some PSUs, but the Corsair HX 650 apparently works fine.
April 21, 2011 2:32:48 AM

GhislainG said:
I may be wrong, but I believe the OP's system powers up with the hp PSU. If everything is connected properly, then hp probably require a PSU having specific characteristics that are not available in the new 850W unit.

Edit: A search on Google seems to indicate that this issue occurs with some PSUs, but the Corsair HX 650 apparently works fine.


Im thinking it is more along the lines of this...that is a great guide but most of is is not applicable to my specific problem. I just want to be able to turn my mobo on with the new power supply and in theory all I should have to do is plug in the 24 pin adapted and turn the power on and the mobo should receive power and the fans should start up. With the old PSU all this works perfectly but the mobo doesnt like something about the new one.

What could the old PSU have that the new one does not? I am getting a new motherboard soon anyway one is actually a name brand not some crap HP product so problem should be solved whenever I can afford the upgrade.
a b ) Power supply
April 21, 2011 2:41:14 AM

jedinegotiator said:
Im thinking it is more along the lines of this...that is a great guide but most of is is not applicable to my specific problem. I just want to be able to turn my mobo on with the new power supply and in theory all I should have to do is plug in the 24 pin adapted and turn the power on and the mobo should receive power and the fans should start up. With the old PSU all this works perfectly but the mobo doesnt like something about the new one.

What could the old PSU have that the new one does not? I am getting a new motherboard soon anyway one is actually a name brand not some crap HP product so problem should be solved whenever I can afford the upgrade.

just the 24pin? you also need the 4 pin 12v connector.
April 21, 2011 3:04:37 AM

To get the computer to boot you need the CPU 4 pin power but just to get the fans going and stuff you only need the main 24pin adapter. I have hooked up the P4 connection I am just saying you dont NEED it for the mobo to power on.
a b ) Power supply
April 21, 2011 3:29:39 AM

Quote:
What could the old PSU have that the new one does not?
I don't know, but a few years ago I had to RMA an Antec PSU because it wasn't compatible with an Intel motherboard (it wouldn't power up). A newer revision of the PSU resolved that issue.
May 1, 2011 2:52:32 AM

Best answer selected by jedinegotiator.
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