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Voltages

E

ecameow

Limp Gawd
Joined
Jan 7, 2004
Messages
230
I posted this in the motherboards section also hope someone can help me out.

Does anyone know what devices use -5v and -12v?

My friend is having problems with the power, he rma'd his power supply and the motherboard and neither of thoes were the problem, any help would be appreciated.
 
none

infact the -5V rail as been removed from the latest ATX12V v2.01 spec
both can safely be ignored they give wild readings without a load on them

what problem?
its entirely possible to have a functional PSU that simply isnt up to the load a config will put on it
thus it will pass any RMA test and yet fail to work properly when employed by the end user
and wattage is no longer a reliable indicator, you need the proper distribution of amps to the right rails as well
 
well his computer wont stay up for longer then 30 seconds or so after post. And the only thing he sees as a problem is the -5 -12v, its a fresh install without internet so its not a virus. any ideas?
 
Heat, power and RAM

if its consistantly shutting down at the same time, Id guess heat
(though it could still be power, if the draw is too high and the PSU is what is heating up)
if its erradically shutting down with various tasks Id guess power
as the load becomes too high for the supply

test the RAM with memtest86+
verify the heatsink is properly seated and pop the side off the case, test it somewhere cool and train a fan on it

as far as power goes
http://hardforum.com/showthread.php?t=823481
run the numbers for the config, and post back with the make so I can look up its amps
 
This is his friend. Here is the deal. I just started up my computer with just the hd i needed for Win XP pro. the cpu fan, and my radeon 9800 pro 256. I still got half the voltages i should have on -5 and -12 voltages. I will run memtest, and see what happens. Could it be windows messing up, maybe need a fresh install? Could it be any device that uses +5 or +12 voltages? this info would be appreciated. :confused:
 
nothing uses those negative voltage rails, which is why they read so erradically
they are not the problem, you can ignore tham

If youll post the make and model of the power supply you have
and what components (mobo cards drives ram ect)
your trying to power, I'll do an audit for you.
 
sorry this took so long, but midterms got in the way.

Computer specs:
Abit NF7-S2
Athlon Braton 2200+
756megs of Cosair PC 3200 DDR400 (1x256 & 1x512)
WD 80gig ata100 8meg cache
Maxtor 200gig ATA133 8meg cache
Liteon 24x CD Burner
Liteon 8x DVD player
Coolmax 5500 silent switching power supply
3 case fans
3.25" floppy
Themlake silent booast cpu fan
ATI 9800pro 256megs

I have replaced or unplugged everything excep for my CPU and CPU fan. When ever i try to install windows it gets to the screen "press enter to install, f3 to quit, etc" as soon as it gets there, boom shuts off. I have also changed all cables.

So all I have to say is HELP!!!
 
well the video card comes out to
13.64A +3.3V
5.41A +5V
0.59A +12V

which I manually entered
http://takaman.jp/D/?M=PbQHQbdPcSASgTKTnUTkG5BHDvHFZAZavPCOP&english
I get
+3.3V rail 13.2A
+5V rail 14A
+12V rail 13.8A
for a total wattage around 300 Watts (keeping in mind that is actual watts and the theoretical maximum, and that its distributed to the right rails)

and the Coolmax 550 is listed at
http://www.newegg.com/app/ViewProductDesc.asp?description=17-159-004&depa=0
+3.3V 28A deduct a third for temperature and you get 18.6A
+5V 55A again 36A
+12V 22A again 14.6A

so technically that supply should be OK, but COOLmax is what most would consider a low average to generic supply,
meaning the rail your the closest on the +12V, might at times be giving that supply a workout, which could impact the stability

for the cost of that supply there are alot of other supplies id choose over it
for instance the new Fortron ATX12V v2.0
 
that suggests heat
and heat impacts the PSU (among other components)
as the supply gets hotter its capacity drops which is why I deducted one third of the amps on all the rails to reflect the difference between the temperature the supply was rated at (25C) and the likely operating temperature (40C)
now if its getting hotter than that, it could have even less capacity and thus there is your power problem

alternately there can be other explainations
the BIOS could be set to shutdown the computer when a certain CPU temperature is reached
there are several thermal cutout schemes employed on mobos these days

what are the case and CPU temperature?
(ideally at both idle and under full load, but give me idle first before risking full load)

PS I need to go to work :p

have you tried popin the side panel and using a big fan to see if it will go past that 30 seconds?
and reseated the heatsink? what thermal grease or pad was used (note a pad is a one time only solution, if a pad was orginally used you would need to clean it off and then apply thermal grease)

did he build this or buy it?
in either case
he built it ...poor heatsink seating
he bought it...heatsink shifted in transit
 
My SiSter's computer will do the same thing... but she has an ECS K7S5A motherboard (SiSter... get it?) with 4 - 6 vented capacitors around the ATX header on the motherboard. I've been meaning to go through and replace the caps, but I don't think the mobo is worth the trouble.

So in short, I would also visually inspect your motherboard and make sure all your caps are good.
 
Jicks said:
with 4 - 6 vented capacitors around the ATX header on the motherboard.

So in short, I would also visually inspect your motherboard and make sure all your caps are good.
Click to expand...

that was a serious issue a little over a year or so ago
the skinny was many mobo manufacturers switched from more expensive Japanese supplier to a new Taiwanese supplier that had incorrectly lifted the formula from the aforemention Japanese supplier :p
with disastrous results, I got lucky, my KR7A was notorious for that problem, but its still going strong, it is however a "dated" issue that is unlikely to be seen in an NF7-S2 ;)
but a close inspection certainly wont hurt, generaql signs are a bulge or split capacitor
 
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