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-5v feed on motherboards...

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-5v feed on motherboards...

Well a short time ago I assembled a computer and when the moment of truth came my computer wouldn't power up (or even give any remote sign that it was doing anything). At First I thought it was the fact that my Enermax Noisetake AX 420W PSU only had 19 pins not 20 on the main ATX lead and my motherboard had 20 (It fit in but one pin was missing). I was then told

Quote

"That missing wire is to supply a -5volt feed to the motherboard. Since most modern boards don't need it, enermax didn't include it in the circuitry"


SPECS:

Motherboard: PC Chips M848A v2.1
Hard drive: Seagate Barracuda 40GB
RAM: 256mb Kingston DDR 400
CPU: AMD Athlon XP2800+ Barton Core
Heatsink: Retail ^
CD Drive: Unknown
Floppy: TEAC Micro floppy Drive
Gfx Card: NVIDIA RIVA TNT2 MODEL 64/64 PRO

What I was wondering was if this Motherboard requires the -5v feed to the motherboard. And if not could you suggest one that does?

http://www.ebuyer.com/customer/products/index.html?action=c2hvd19wcm9kdWN0X292ZXJ2aWV3&product_uid=6...
25 REPLIES
Brickinit
Grafter
Posts: 450
Registered: 06-08-2007

-5v feed on motherboards...

when you say it doesn't power up do you mean nothing at all,no fan on the power supply, or does it get passed that?
N/A

-5v feed on motherboards...

No fan or anything...
Brickinit
Grafter
Posts: 450
Registered: 06-08-2007

-5v feed on motherboards...

that points to your power suppy, even if you had problems with the motherboard you would still have power.
N/A

-5v feed on motherboards...

Sorry I made a mistake, I just went upstairs and plugged in the PSU without the Motherboard or anything attatched and the fan spins then stops (thinking about it it does it with the MOBO attatched also)

The thing is that it does not seem to spin every time I flick the [O\I] switch, is this normal?
N/A

-5v feed on motherboards...

Are you sure the mainboard is seated correctly in the case.

If the board uses brass or silver pillars screwed into the chasis make sure that they are where they should be and that none are causing the underside of the pcb to short out. Easily done and PC Chips boards are notorious for not lining up correctly.

If you have any way of testing the PSU with an old mainboard on a bench or table (bearing in mind the risk of shock) then this might be an option. It would at least confirm the reliability of the PSU.

Regards

Mark
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-5v feed on motherboards...

Soz,

You replied while I was typing.

That sort of points to the PSU being iffy then.

Shouldnt be too hard to replace.

Mark
N/A

-5v feed on motherboards...

So the fan should spin every time? The PSU does have some kind of smart fan system so it's rather confusing....
Brickinit
Grafter
Posts: 450
Registered: 06-08-2007

-5v feed on motherboards...

the fan on the power supply should remain on constantly as long as the supply is running it doesn't have a thermol switch or the likes
N/A

-5v feed on motherboards...

I think you might be misunderstanding me, I am talking about the switch on the back on the Power supply unit itself not the switch for the computer on the front of the case.

When I press the switch on the back of the power supply unit the fans spins round once and sits idle.

When I have the computer all plugged up and I press the switch on the front of the case with the switch on the back of the PSU on also i get nothing.

The thing is I know that the fan is not supposed to constantly spin round when the switch on the back is on as that would mean my PSU fan would never stop Wink but it is supposed to keep spinning when the PC is on. The thing is that my PSU might not be recieving the correct signals to tell it that the PC is actually on...(I'm not sure if this would be a result of a iffy PSU,MOBO or connection to the case)

I might be talking complete rubish so i would be grateful if you could help me out...
Brickinit
Grafter
Posts: 450
Registered: 06-08-2007

-5v feed on motherboards...

that doesn't sound right have you been to the psu web site if they have one, or even better take the psu back to where you got it to have it checked out.
do you have another atx psu you can try on the mb?
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-5v feed on motherboards...

Please look at the post above as I heavily editted it ^.

I do have another ATX PSU but it's not even good enough to run my MOBO Tongue
holdtight
Grafter
Posts: 1,634
Registered: 15-06-2007

-5v feed on motherboards...

Just a thought before you take the psu out, as this is a system you have

just put together go through the mobo manual and triple check that you

have all the case wires for the front power switch reset switch on light and

hdd light plugged into the correct plugs on the m`board as plugging them in

wrong can cause your system not to power up
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-5v feed on motherboards...

I don't have the following connection wires installed on the from panel:

HD_LED_P
HD_LED_N

SUS LED
SUS LED

And I don't know where to find the connectors from the case and what they would be labelled...

I have a few connector from the case I have not used and they are:

VCC
TPB-
GND X2
TPA +
TPB +
TPA -
----------------
GND
DATA 2
DATA 2
VCC 2
----------------
R OUT
R IN
GND
MIC IN
L OUT
L IN
GND
MIC IN
---------------
GND
DATA 1
DATA 1
VCC 1
---------------
Also I was just re-reading reviews of my case and came across the following:

Quote
Now here comes the real killer, it DOES NOT HAVE A HDD INDICATOR. I couldn't believe it. I mean honestly how much exta would it have cost to incorporate a HDD light indicator
Brickinit
Grafter
Posts: 450
Registered: 06-08-2007

-5v feed on motherboards...

i've been trying to find out a little bit about this psu unfortunatly the makers web site is still under construction, however there is a bit about it here
http://www.overclockers.co.uk/acatalog/Online_Catalogue_Enermax_111.html
and it does indeed have a themostat and rheostat with a manual or auto fanspeed control do you still have any manuals for it even if it's just to tell you which connector should be at which voltage, that you can check

there is also this site which seems quite clued up on enermax psu's
http://www.over-clock.com/ivb/