24pin psu -> 20pin mobo problem

[Melx]

ok, i have fortron blue storm 500w with 24pin (20+4pin atx), its all fine with this psu.
mobo is 939dual-sata2 with 20pin atx
but now i upgrade to fortron 550w and it has plain 24pin atx, i cut those 4pin so that now i can use it on my 20pin mobo but got problem.
when i press power switch, it start for 1sec max and then shutdown, i press power again it wont do anything, if i unplug power cable for 10-15sec and plug it in same thing again, first time starts system max 1sec and power off, when i press power again, silence...

[Dngrsone]

That is a classic indication of an overcurrent condition-- there's a short which causes the PSU to kick off to protect itself and the rest of the equipment.

Check your motherboard installation and see if you can find a place where the motherboard is toucing the case where it shouldn't be or a metal stnadoff that needs an insulating washer.

Failing that, you should remove all non-essential equipment and try to isolate the shorted component (fans are prime culprits).

[Melx]

i dont use case so there must be some other problem.
i think myself, aint there a way that psu must use all 24 pins, that those 4 pins must be used too :

[Dngrsone]

Some boards have a seperate 4-pin connector that you need to plug in, but the PSU doesn't have to have a load on those pins as far as I know...

Like I said, the behaviour you described has always been caused by an overcurrent in my experience-- a short-circuit or, rarely, a low-impedance load.

[Melx]

Originally Posted by Dngrsone

Some boards have a seperate 4-pin connector that you need to plug in, but the PSU doesn't have to have a load on those pins as far as I know...

if u mean p4 connector then its connected, i tried w/out it and same.

Originally Posted by Dngrsone

Like I said, the behaviour you described has always been caused by an overcurrent in my experience-- a short-circuit or, rarely, a low-impedance load.

at the moment i use my old blue storm and its all ok.
overcurrent means exactly what ? short-circuit ?
anyway i think there aint anything wrong with electric system cos its all works ok with blue storm, just dont start with new psu.
psu and mobo are separated so there cant be too any problem

i tried this and psu works w/out problem so there cant be anything wrong with psu itself.

Originally Posted by Dngrsone

...or, rarely, a low-impedance load.

u mean i must add more fans and hdd's like ?

[Steve50_a]

"u mean i must add more fans and hdd's like ?" No you don't need to ad anything.
"i cut those 4pin so that now i can use it on my 20pin mobo but got problem.
" You cut the 4 pin off? Which 4 pins did you cut off? If you cut 4 pins off the wrong side, the PSU will not work when it's plugged into the MB ( the MB won't boot ).

[Melx]

i cut those like on this pic
http://stcomshop.co.kr/asusclub_imag...45GA/24pin.gif
its all right, i have checkd everything 10 times
really dont know wtf is wrong, everything is like ok but is not too

[murrattija]

have you tried with an adapter so you have all the pins in use?

[Jimmer411]

Originally Posted by murrattija

have you tried with an adapter so you have all the pins in use?

$5 part so you dont have to cut anything. i had to do this with my antec 550 in my other pc.

[Steve50_a]

Ok, you just seperated the connector at the joint. With the MB out of the case, have you tried shorting the PS pins? ( I'm guessing you have ) And the old PSU works fine? If so the psu is bad. 1 other thought, does the cooling fan inside the PSU turn on and run?

[Dngrsone]

Originally Posted by Melx

if u mean p4 connector then its connected, i tried w/out it and same.
at the moment i use my old blue storm and its all ok.
overcurrent means exactly what ? short-circuit ?
anyway i think there aint anything wrong with electric system cos its all works ok with blue storm, just dont start with new psu.
psu and mobo are separated so there cant be too any problem

i tried this and psu works w/out problem so there cant be anything wrong with psu itself.

u mean i must add more fans and hdd's like ?

That's all well and fine... the PSU runs up without a load on it... but fails when you try to power something? I'm thinking the PSU is bad then.

[Melx]

Originally Posted by murrattija

have you tried with an adapter so you have all the pins in use?

you mean that psu wont start if all pins are not connected, i was thinking same thing myself, is it possible cos this psu dont have separatable 4pin, mb this is the problem

[arbiter]

yea not recommended but it works i just got a new psu for £17 550w sata and pci-e connection 24pin, 12v-33a 5v-40a nice lol very pleased

[Steve50_a]

"you mean that psu wont start if all pins are not connected, i was thinking same thing myself, is it possible cos this psu dont have separatable 4pin, mb this is the problem" So, you are saying you actualy had to cut the 4 pins off the end of the connector? If so you may have cut off necessary pins. There is an adapter 24 to 20 pin adapter that you need. Post a picture of that connector. Most PSUs that I have seen, Coolermaster comes to mind, include such an adapter with the PSU in the box.

[Melx]

yes i cut those extra 4pin (12|5|3,3|com) end of connector cos it didnt fit, i dont have adapter yet, but one arrives tommorow, wll see if this works .

[Steve50_a]

Melx, you should be good to go with the adapter.

[Melx]

and the end of this story is that this psu wont work with 20pin mobo, adapter didnt help, only 24pin (nf4) mobo starts up with this, so gonna change my mobo