Solved Changed PSU,when connected 24pin,no power

Tsunamijhoe · Jan 29, 2013

Hey guys
I exchanged psu's in my computers due to cable needs,and i have replaced a 500w antec with a 500w northq (NQ-4775-500s), now,i tested the psu with a multimeter,and all is a-ok across the board, however,whenever i plug the psu into the motherboard (Gigabyte GA-H55-UD3H), 24pin and 4pin 12v atx nothing happens, no fans start spinning,no light on mb,nothing. I can get fans spinning and everything if i short out the power and ground on the 24pin connector,but when same is connected to mb,nothing happens.

Now,this motherboard worked absolutly fine with the antec psu. The antec had a 8pin 12v atx i needed on another pc,and this gigabyte mb only need a 4pin 12v atx,so it should be a perfect fit.

Anyone have any ideas? Other than the mb suddenly is fried or something

Erick Aguilar · Jan 29, 2013

Are you sure you wired the front panel connectors properly? Does your motherboard have a powerswitch?
Have you tried with the OLD psu again and see if the computer starts?

Solarstarshines · Jan 29, 2013

Erick Aguilar said:
Are you sure you wired the front panel connectors properly? Does your motherboard have a powerswitch?
Have you tried with the OLD psu again and see if the computer starts?

If he just pulled out the Psu the front panel pwr reset buttons should be in tact

are you sure your 8 or 4 pin connection is in tight on the MB sometimes those tend to be hard to lock in

double check all connections and switches and make sure your board is grounded that would make you also think you have to juice

Tsunamijhoe · Jan 29, 2013

Everything is 100% connected correctly and firmly in place,i cant even get power shorting out the mb power switch connectors,it is as if no power gets through the 24 pin connector.
There is no light on the mb either,and the other psu is powering another system,so i havent tried putting it back in,although it shouldnt matter,as all my psu work fine,all connectors deliver the rated volts continuously,and that leaves the mainboard,cpu,ram.

Will the mb power on (mb light at least) if no cpu and ram is in it?

Erick Aguilar · Jan 29, 2013

Solarstarshines said:
Erick Aguilar said:

Are you sure you wired the front panel connectors properly? Does your motherboard have a powerswitch?
Have you tried with the OLD psu again and see if the computer starts?

Click to expand...

If he just pulled out the Psu the front panel pwr reset buttons should be in tact

are you sure your 8 or 4 pin connection is in tight on the MB sometimes those tend to be hard to lock in

double check all connections and switches and make sure your board is grounded that would make you also think you have to juice

Well some people like to clean the inside of their computer throughly when swapping components.
But then again it may be just be me

Erick Aguilar · Jan 29, 2013

Tsunamijhoe said:
Everything is 100% connected correctly and firmly in place,i cant even get power shorting out the mb power switch connectors,it is as if no power gets through the 24 pin connector.
There is no light on the mb either,and the other psu is powering another system,so i havent tried putting it back in,although it shouldnt matter,as all my psu work fine,all connectors deliver the rated volts continuously,and that leaves the mainboard,cpu,ram.

Will the mb power on (mb light at least) if no cpu and ram is in it?

No, you need to have at least CPU and one stick of ram.

I recommended you to try the other PSU to check if it might be the motherboard.

braddersz · Jan 29, 2013

Have you checked the back of the psu for an off/on switch?

along with the 24pin,

there should be a 4-8 pin connector, usully top left of motherboard.

Tsunamijhoe · Jan 29, 2013

braddersz said:
Have you checked the back of the psu for an off/on switch?

along with the 24pin,

there should be a 4-8 pin connector, usully top left of motherboard.

Dude, please read posts before answering. Ofcourse both the 12v 4pin connector, and the 24pin are attached, as well as the power switch on the psu is on.

Please check my above post for addition to this conundrum

Solarstarshines · Jan 29, 2013

The Motherboard in question should atleast admit a beep of some sort when it has power
if there was no beep there is something wrong the connections are secure the next step he can try it in another rig

and see if he can get it started if not i would think the PSU doesn't have enough power and he needs to replace it with something that can

Dwarf · Jan 29, 2013

The first thing to do would be to check (and double check) all motherboard connectors, especially the front panel ones. Once you have ascertained that everything is as it should be, try again. If still no go, you can (as a last resort) momentarily bridge the appropriate terminals directly on the main ATX power connector. The terminals to bridge are PS_ON# (Green wire) and one of the COM (Black wire). See image below:

Tsunamijhoe · Jan 29, 2013

Solarstarshines said:
The Motherboard in question should atleast admit a beep of some sort when it has power
if there was no beep there is something wrong the connections are secure the next step he can try it in another rig

and see if he can get it started if not i would think the PSU doesn't have enough power and he needs to replace it with something that can

OK,if you would just read my previous posts instead of only reading the very last post,you would understand the predicament,and not suggest something that has been tried and testet.

Please understand, there is NOTHING wrong with the psu,the psu works on 2 other computers,it works when tested with multimeter. The psu in question does however NOT work with the gigabyte mainboard,which is why i am confused,as it should work fine unless mainboard is fried.

I can get psu fans and everything to spin if i short pin9 and a groundwire,but as soon as 4pin 12v atx and 24pin power is connected to mainboard nothing happens,not a single beep or anything

Dwarf · Jan 29, 2013

Have you tried bridging the ATX terminals whilst the connector is plugged in, as I described above? Another thing to try is to disconnect the reset switch from the front panel header, just in case there is a fault with it and it is constantly holding the motherboard's reset line to ground.

Tsunamijhoe · Jan 29, 2013

Dwarf said:
Have you tried bridging the ATX terminals whilst the connector is plugged in, as I described above? Another thing to try is to disconnect the reset switch from the front panel header, just in case there is a fault with it and it is constantly holding the motherboard's reset line to ground.

OK, this is beginning to freak me out. I pulled the mainboard (gigabyte),hooked it up to my brand new corsair 750GS,and mainboard lit up like a xmas tree,cpu fan began spinning,and so on,so mainboard works.

However, if i connect the same board to the northq psu,nothing again happens.

Now, if i bridge pin 9 and a black ground,i get psu fan spinning. If is use a multimeter and test the cables,i get 5v where 5v should be,i get 12v where 12v should be,i get -12v volt,i 3,5v , so why the hell doesnt this psu work with my gigabyte board?
I have no front cables attached,i tried to short the mb pins manually to simulate power button,nothing happens, but this worked on the corsair psu,so something is definitly wrong..

Also,if i connect the "faulty" psu back to the asus mainboard the asus work fine,you see why i am confused?
It is very strange.

*UPDATE*

AHA,i tried your suggestion with the bridge over green to black while connector is attached to mainboard,and it worked, motherboard lighted up,cpu fan began spinning,and fan on psu also spun.

So,what is wrong,and how can i fix it?

kbrady1979 · Jan 29, 2013

I have found that some power supplies just don't work with some motherboards. Good PSU.....good motherboard........but they just won't work together. It happens, and I wouldn't try to make it work, just put another psu on that motherboard and make sure you make a mental note about them not working together.

bassfisher6522 · Jan 29, 2013

Sounds like a faulty plug on the PSU. Personally I've never heard of that brand and wouldn't use it. I would send it back and get one from the top 5 makers.

Tsunamijhoe · Jan 29, 2013

kbrady1979 said:
I have found that some power supplies just don't work with some motherboards. Good PSU.....good motherboard........but they just won't work together. It happens, and I wouldn't try to make it work, just put another psu on that motherboard and make sure you make a mental note about them not working together.

Really? That sounds kinda strange. This psu provides ALL the designed power to the correct connectors,so that makes no sense it shouldnt work, that is like saying it is the will of god,which i refuse to believe

.. Anything has an explanation, you just have to look hard enough.

And by your logic,there is no guarentee a new psu would work anyhow,which is what standards are for,to make sure stuff fit together

bassfisher6522 said:
Sounds like a faulty plug on the PSU. Personally I've never heard of that brand and wouldn't use it. I would send it back and get one from the top 5 makers.

then why have this psu worked flawlessly with 2 asus boards?

But, something is clearly going on with this psu, i just would like to know what,and why

Dwarf · Jan 29, 2013

Tsunamijhoe said:
*UPDATE*

AHA,i tried your suggestion with the bridge over green to black while connector is attached to mainboard,and it worked, motherboard lighted up,cpu fan began spinning,and fan on psu also spun.

So,what is wrong,and how can i fix it?

I wonder if those terminals aren't making good contact with each other (that is, the PS_ON# terminal in the PSU connector and the corresponding pin in the motherboard socket. What happens if you try turning the computer on with the normal power switch whilst waggling the green wire?

Tsunamijhoe · Jan 29, 2013

Dwarf said:
Tsunamijhoe said:

*UPDATE*

AHA,i tried your suggestion with the bridge over green to black while connector is attached to mainboard,and it worked, motherboard lighted up,cpu fan began spinning,and fan on psu also spun.

So,what is wrong,and how can i fix it?

Click to expand...

I wonder if those terminals aren't making good contact with each other (that is, the PS_ON# terminal in the PSU connector and the corresponding pin in the motherboard socket. What happens if you try turning the computer on with the normal power switch whilst waggling the green wire?

I cant "jimmy" the start sequence,i have tried. i tried manually shorting the front header power switch connectors while fiddling with the 24pin connector,and every wire seperatly,i cant get it to start..

Should i just take this as a "loss" and throw this thing out,and buy a new one?

I am still curious though as to why this doesnt work

Erick Aguilar · Jan 29, 2013

Tsunamijhoe said:
Solarstarshines said:

The Motherboard in question should atleast admit a beep of some sort when it has power
if there was no beep there is something wrong the connections are secure the next step he can try it in another rig

and see if he can get it started if not i would think the PSU doesn't have enough power and he needs to replace it with something that can

Click to expand...

OK,if you would just read my previous posts instead of only reading the very last post,you would understand the predicament,and not suggest something that has been tried and testet.

Please understand, there is NOTHING wrong with the psu,the psu works on 2 other computers,it works when tested with multimeter. The psu in question does however NOT work with the gigabyte mainboard,which is why i am confused,as it should work fine unless mainboard is fried.

I can get psu fans and everything to spin if i short pin9 and a groundwire,but as soon as 4pin 12v atx and 24pin power is connected to mainboard nothing happens,not a single beep or anything

If you do not know if the mainboard is fried, I cannot understand why won't you test another PSU on the motherboard, NOT the PSU, test the motherboard with another PSU. I don't get why that is so hard to understand.

Tsunamijhoe · Jan 29, 2013

Erick Aguilar said:
Tsunamijhoe said:

Solarstarshines said:

The Motherboard in question should atleast admit a beep of some sort when it has power
if there was no beep there is something wrong the connections are secure the next step he can try it in another rig

and see if he can get it started if not i would think the PSU doesn't have enough power and he needs to replace it with something that can

Click to expand...

OK,if you would just read my previous posts instead of only reading the very last post,you would understand the predicament,and not suggest something that has been tried and testet.

Please understand, there is NOTHING wrong with the psu,the psu works on 2 other computers,it works when tested with multimeter. The psu in question does however NOT work with the gigabyte mainboard,which is why i am confused,as it should work fine unless mainboard is fried.

I can get psu fans and everything to spin if i short pin9 and a groundwire,but as soon as 4pin 12v atx and 24pin power is connected to mainboard nothing happens,not a single beep or anything

Click to expand...

If you do not know if the mainboard is fried, I cannot understand why won't you test another PSU on the motherboard, NOT the PSU, test the motherboard with another PSU. I don't get why that is so hard to understand.

I DID ALREADY,with my corsair GS700,mainboard works fine

Solved Changed PSU,when connected 24pin,no power

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