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View Full Version : help please! no power after rebuild



BillIrwin
05-06-2006, 04:52 PM
ok I replaced mobo/cpu/ram/video card in an upgrade. Checked abd double checked all leads, power supplies etc plugged in according to mobo manual. Go to boot up - absolutely nothing - apart from a faint humm of power in the power supply.

No drives spinning, no fans, nothing. Have plugged & unplugged power connectors to mobo. It doesn't have a led on it like some to show there is power to it. So I'm stumped as to where to start looking for defective components. Doesn't seem like the power supply would die at the same time as I do an upgrade does it?

Any thoughts much appreciated, Bill

tweak'e
05-06-2006, 04:58 PM
details please. what was the old system? what powersupply do you have? and what is the new hardware?

BillIrwin
05-06-2006, 05:07 PM
details please. what was the old system? what powersupply do you have? and what is the new hardware?
ok.. old was Asus P4B533, P4 - 2.0, 512 MB ram, nvidia 5200 video card. Replaced that with Gigabyte GA-K8NF9, AMD64 - 3200, 2x 512 Adata PC3200, Gigabyte X700 pro video. Everything else is the same - power supply is 320 w.

thanks, Bill

Speedy Gonzales
05-06-2006, 05:25 PM
Is this the GA-K8NF9 Ultra?

The PSU seems a bit low for the new mobo / system.

Have you plugged the ATX 12v connector from the PSU in the ATX slot/adapter on the motherboard??

BillIrwin
05-06-2006, 05:30 PM
Is this the GA-K8NF9 Ultra?

The PSU seems a bit low for the new mobo / system.

Yes it is the ultra - it says min 300w psu. If it is not enough will is cause these symptoms - ie completely dead?


Have you plugged the ATX 12v connector from the PSU in the ATX slot/adapter on the motherboard??

yes, have done that thanks

gibler
05-06-2006, 05:41 PM
Might be just a motherboard that is dead on arrival (yep it does happen).

Double-check the power/reset leads to the motherboard from the front of your case (see what the marking say on the mobo itself, sometimes the manuals are just plain wrong). Try a different CMOS battery, check nothing is shorting out the board.

Try a different video card (or use on-board if it has it).

Speedy Gonzales
05-06-2006, 05:47 PM
And I take it you've connectd an IDE / SATA hdd in the case somewhere as well?

Is it beeping, if there's a speaker connected to the header on the mobo?

You made sure the ram is in the right slots?

BillIrwin
05-06-2006, 05:48 PM
Might be just a motherboard that is dead on arrival (yep it does happen).

Double-check the power/reset leads to the motherboard from the front of your case (see what the marking say on the mobo itself, sometimes the manuals are just plain wrong). Try a different CMOS battery, check nothing is shorting out the board.

Try a different video card (or use on-board if it has it).

thanks - I was a bit unsure of polarity on the power/reset leads. There is generally white/green or blue or black/red. I assumed neg. is white or black, but when it didn't boot first time I reversed them, still no go.

The leads I'm assuming are neg (white or black) have a little triangle & 'S" mark on them, but I don't know what to make of that

BillIrwin
05-06-2006, 05:50 PM
And I take it you've connectd an IDE / SATA hdd in the case somewhere as well?

Is it beeping, if there's a speaker connected to the header on the mobo?

You made sure the ram is in the right slots?

yep. 2x HDD to IDE 1, CD to IDE 2, FD connected

RAM in slots 1 & 2 as advised in manual

No beep, dead silence...

tweak'e
05-06-2006, 05:56 PM
PSU is way under spec. you might get away with it if its a really good one but i doubt it will last.

one old trick is to hit the reset switch.

make sure you don't have keyboard powerup on (it may be called something else, it enables power on from keyboard instead of case power button)

you didn't fall for the newbie mistake of not useing or incorrectly placing the motherboard standoffs ?

BillIrwin
05-06-2006, 06:02 PM
PSU is way under spec. you might get away with it if its a really good one but i doubt it will last.

one old trick is to hit the reset switch.

make sure you don't have keyboard powerup on (it may be called something else, it enables power on from keyboard instead of case power button)

you didn't fall for the newbie mistake of not useing or incorrectly placing the motherboard standoffs ?

thanks - I see a new PSU is on the shopping list

Standoffs - old mobo used 6, I repositioned these, but still had spaces for 3 more. Didn't have the exact ones but found some metal spacers that fit. I can't see that they are in contact with anything underneath but will go have a look.

BillIrwin
05-06-2006, 10:30 PM
update: I unplugged everything except cpu/ram/video, still no power up. Then disconnected all power leads - shorted out the green & black leads of the ATX power plug which kicked the PSU in to life (apparently this is the same as hitting the power switch). With this now running, I tested all the voltages - they seemed ok - so now I'm guessing it's a dead mobo. That's about all that it can be, right?

tweak'e
05-06-2006, 11:28 PM
when you shorted the leads was it pluged into the mobo? ie is the pc running?

you sure you got the power switch wired correctly?

when you turn on the pc the motherboard normally sends back a power good signal to the psu. if the psu dosn't get that it won't run. i've had it when there isn't enough standby voltage for the mobo to run to be able to start the psu. (sounds kinda werid but the mobo basicly runs all the time and the power switch simply tells the mobo to turn the power supply on) i had to replace the psu. i would try bigger psu first as you will need it anyway.

BillIrwin
06-06-2006, 07:57 AM
when you shorted the leads was it pluged into the mobo? ie is the pc running? you sure you got the power switch wired correctly?.

no - everything was unplugged. But I did try plugging the power back in to the board and jumping the pwr switch connectors in case the power button was dodgy. No luck. I'm going to try a new psu next. Many thanks for all the advice.

FoxyMX
06-06-2006, 06:42 PM
I have had a dead CPU cause similar symptoms, except that the fans started running for a couple of seconds. Apart from that everything else was dead.