PCTech Forums

We had a power failure.
Now when I start my PC it will not boot.
The flgoppy drive doesn't give the usual whirr noise when initialising, and the monitor staiys in stand-by mode.
I can't hear thet hard drive ticking away like normal (on start) and the drive indicator led goes off after 10 - 15 seconds, but nothing is going on.
I have put my XP disc in but nothing is happening.
Do you reckon this is a drive or mobo failure?
Any ideas on what to try?

jemmo,

Try unplugging your systems power cord from the surge protector/outlet.
Wait at least one minute before you plug it back in.

Thanks Gecko, but that has made no difference - same symptoms.

jemmo,

Sorry that didn't work for you.
It sounds like it's not even getting to POST (power on self test).
That would mean hardware failure, power supply, ram or motherboard most likely.
Although it could be a daughter card like sound card, network card, modem, video card...

It's a process of elimination at this point, if you have an extra power supply I would try that first.
Otherwise try removing one of your RAM sticks and try, working you way through all your ram.
If that doesn't find it then try removing your daughter cards one at a time.

Thanks Gecko.

I have checked the RAM and ruled that out as the symptoms remain.
I have measured the voltage going into the drive on the power connector and have;
Yellow = 12.15 volts
Black = -0 volts (minus zero - is that correct?)
Black = -0 volts
Red = 5.07 volts

I have also checked the voltage going to the mobo in the 4-pin connector and according to the mobo manual those voltages are correct (0 volts on two pins, 12 volts on two pins). It looks like those voltages are corect for ATX power supplies.

I guess for the next step I really need to check all 20 connections on the ATX Power Connector and confirm all voltages are as they should be?

I have checked the voltages going into the mobo using the info from the mobo manual.
Table below shows the details and the 'Actual' column shows any potential (no pun intended) differences;

Pin Definition..................Actual
1 3.3V
2 3.3V
3 GND
4 VCC............................5.1V
5 GND
6 VCC........................... 5.1V
7 GND
8 Power Good .................4.08V
9 5V SB (Stand by +5V)
10 +12V
11 3.3V
12 -12V
13 GND
14 PS_ON (Soft On/Off)
15 GND
16 GND
17 GND
18 -5V
19 VCC............................5.1V
20 VCC............................5.1V


Does the 'Power Good' voltage look correct? I read somewhere on the interweb this is normally 9V but does this depend on the mobo/psu/country of operation?

I have also removed all of the daughter cards and that made no difference so if the voltages above are all correct, then it looks like hard drive or mobo.

And to cap it all someone tried to steal my car yesterday - smashed passenger door window (denting the window suround), damaged the drivers door lock and mechanism and ripped off the steering cowling. Great start to the year eh?

Jemmo,

It is not the HDD, your system is not booting that far, besides you would get an error related to no OS installed or could not read drive.

As for your power supply readings, the Power Good rail should be +5.0 volts.
This is an indication that one of your +5.0 rail is is not running at full voltage.
The Power Good rail is like a self test for prior to powering the motherboard itself.
If the Power Good rail is not within range then no power will be sent to the MB.

A bad capacitor or a shorted resistor in the power supply or MB could cause this low reading.

Thanks Gecko

I'm going to drop the hard drive into a spare machine at work and test that it boots up. If so then it's a trip to PC World for a new psu.

I have had the psu tested (at PC World) and they reckon it's fine.
The guy said to remove all RAM sticks and boot up the PC. If the mobo is okay I should get some warning bleeps. Is this correct?

If so then it looks like the mobo is at fault (no bleeps), but I want to check as it's the most expensive fix.

jemmo,

That is correct if there is no ram installed you should receive a beep.
As long as the PSU is functioning correctly and you have a speaker hooked to the motherboard.

Thanks for confirming Gecko.
Looks like a new mobo it is.
Only problem is my current one is socket 478 with 5 pci slots (4 used) and I guess things have moved on as I can't seem to find anyone that stocks a same/similar model. So it's looking like a rebuild with new mobo, procesor and RAM.

Oh joy!

jemmo,

You might think about replacing that PSU as well, the demands from the new components might be more than your current PSU can deliver. Besides if you make a PSU the first item you buy then you can confirm the bad MB verses the PSU.

Good luck

Well I went for the cheaper option (on this occasion - having just had to pay nearly a £1000 on repairs to my wife's car and excess insurance payments after someone broke into my car and tried to make off with it) and sourced a mobo same as the one I have but the next release. Couldn't find one in the UK - it came from China!
I have a question about RAM - I currently have a 1Gb stick, and two 512mb sticks. The mobo can take 4Gb.
Is it best to spread the RAM evenly across the sockets (1Gb in each slot) and does it make a difference to the type of RAM? For example, I have PC3200 RAM (whatever that is). Is it best to stick to PC3200 or does it not make any difference?