Wondering if my PSU works

Asus P7p55d deluxe desktop board
August 28, 2010 at 20:47:41
Specs: Windows 7, Intel Core i3-530 Clarkdale 2.93GHz
Putting together some new parts into a chassis, psu, optical drive. I took one of the 4-plug connectors from my old PC (while it was running) and got the lights and fans in the CM Storm Sniper to light up.

Then I put in the new Thermaltake XT 775W, there is no main board so I just did the same thing: used the modular plugs for fans and SATA optical, but no power.

The "standby" lamp is lit, bo none of the other 2: pg signal and temperature. The temperature light off is good, but I don't know what pg signal is.

Does the Thermaltake Toughpower XT power supply require the main connector to make any power or is the psu DOA???

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August 28, 2010 at 21:26:04
"I took one of the 4-plug connectors from my old PC (while it was running)"

fastest way ever to fry either the powersupply or whatever you plug it into.

Rule 1. Never connect anything inside a PC case while mains power is connected.

Now if there is no mainboard in this new case then you will not get any response from the PSU. In order to start up the PSU you would need at a minimum to bridge the green wire of the 20/24 pin motherboard connector to one of the black wires. Use a paperclip bent to U shape to insert into the two connector pins.
Make sure the mains power is disconnected until you have inserted the paperclip. Turn off the power before removing the paperclip.

Goin' Fishin' (Some day)

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August 28, 2010 at 21:26:36
Did some research, I think i got it. but I am not PC literate enough to know "exactly" what this means:

Newer form factors, starting with the ATX/NLX, and including the SFX and WTX, have changed the way the power supply is turned on and off. Instead of using a physical switch, these systems are turned on by a signal from the motherboard telling the power supply what to do. In turn, the motherboard can be told to change this signal under software control. This is what allows Windows to shut the power down to a PC, or what allows such features as turning a PC on from a button on the keyboard. This feature is called "Soft Power" and the signal that controls the power supply is called "Power On", or alternately, "PS On" or "PS_On".

I read this to mean that the main board tells the psu to actually "power on" with this "soft power" feature.

So... no main board no power output by psu.

Is this correct???


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August 28, 2010 at 21:48:06
Thanks Richard with the low fan voltages I did not think it would be a problem. Still... I know not the smartest thing, but shorting wires on the wire comb sounds a little iffy, as well. Anyways, I won't try your suggestion, but I think I have an answer.

sniper lights in action

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Related Solutions

August 29, 2010 at 00:25:27
Bridging the green/black wires on a PSU is a commonly used simple test and to my knowledge no-one has ever reported damage resulting from this procedure.

It is far less dangerous than your initial attempt at testing by plugging in a live molex connector into the peripherals of your new box.

Goin' Fishin' (Some day)

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August 29, 2010 at 03:48:16
So... no main board no power output by psu.

That's basically it! Even when the computer is turned off there is still some power going to the motherboard.

The on/off switch on the front of the computer is itself connected to the motherboard and is a logic switch, not a physical switch. It does the same job in a roundabout way as shorting the green and black wire.

Have a read of this:




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August 29, 2010 at 14:21:12
Good info thanks guys. Richard, we got off track. I only tested the fan/leds in the new chassis by tapping the 4-pin on the old compaq (as per video). This is no worse than plugging in a live fan connector that may have come loose, so we cool there.

Then, I installed the new PSU (as per OP) and wanted to see the bling... but no bling - because no pg signal. I'll try to test it, cause those leds look so cool.

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August 29, 2010 at 14:26:42
Thanks Stuart... I found that site while looking into the psu thing. Exactly the kind of stuff I need need.

paperclip trick

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