View Full Version : Dead CPU or MB?

21-08-2002, 12:46 PM
I've been installing a new HDD and repartitioning the old one. So I've been fidling with the innards of my computer. Anyway, I switched the computer off before having dinner, then switched it back on again later on.
However, when I switched it on, nothing happened at all. The activity light and HDD light was on but nothing was happening. The CPU and PS fan was also going, and so was the MB LED lamp and the Skymedia LED. So I guess the circuits of the MB must still be OK. The BIOS screen never came up, the FDD and CD never spun to search for a boot disk etc.
There was definitely no burning smell and no sparks seen when I switched it on 'cos the case cover was off. Here's the next bizzare thing. When I switch it off and back on again, the CPU fan won't go at all this time unless I switch the mains off.
I thought that if the problem was with the components at least the BIOS screen should come up with a warning of some sort.

My current set up:
ASUS A7V-E M/board, Athlon 1GHz, 256MB PC133 RAM, Quantum Fireball AS and Maxtor Diamond Plus HDDs, Geforce 2-GTS VGA card, SB Live! Value, Dynalink modem, Telemann Skymedia SM200D, IEEE1394 card
So, any ideas?

Many thanks in advance.

21-08-2002, 01:39 PM
first thing, check the leads. also check you havn't bumped any jumbers.

what power supply do u have? sounds like powersupply fault. what happens when you disconnected all the drives and cards?

21-08-2002, 01:49 PM
Done all that. Disconnected and reconnected all power leads and data cables.
Installed a new 300W PSU as well prior to this happening and it was running fine. As I said, when this problem occured, the PSU and CPU fans were still going (as were the m/board LED and PCI card LED lamps).
When I disconnected the HDD from the m/board and started up the computer, samething happened. No BIOS screen... just absolutely nothing.

21-08-2002, 02:34 PM
forgive me i'm a little slow today. i forgot to add to check the video card is slotted in correctly. easy enough to bump it while changeing leads over. with no pic it makes the pc look dead.

failing that, the usual remove everything from pc, install a good known vid card, cpu + heatsink on/off switch, reset the bios and see if you get bios coming up on screen(it will get error due to no ram) don't forget to check jumbers are set correctly.

also check that you havn't dropped a screw down behind the motherboard(shorting it out)

21-08-2002, 07:50 PM
Dare I ask whether the monitor screen is switched on ?

21-08-2002, 09:10 PM
Still possible you have a faulty power supply. If the power good sensor detects a problem it will not allow the PS to provide power. Don't try and get into the PS unless you KNOW what you are doing. Electricity is rather unforgiving. A local electrical shop might test it or your friendly computer dealer. Wouldn't recommend you try it on another MB in case it is at fault. Best of luck.


21-08-2002, 09:24 PM
Sure the IDE cable isn't on upside down?

22-08-2002, 11:14 AM
Many thanks for all the replies.
Firstly to set the record straight, I'm not a newbie with computers and in fact assembled this computer some years ago.
There's nothing wrong with the PSU as it is brand new and the MB circuits seem to be alive - the MB LED lamp is on and the activity lamp and HDD lamp is on when I switch the computer on. Also, the LED lamp on the Skymedia card is on. The case fan. CPU fan, and video card fan goes on as well.
The display card is in place as are all the other PCI cards. The monitor is switched on as well.
The only thing that lacks avtivity are all the drives (CD/FDD/HDD) and the fact that nothing comes up on the screen - not even the BIOS screen.

So, does that help at all?

22-08-2002, 11:24 AM
This doesn't help but I continue to have a very similar problem on one PC. After having gone through a normal shutdown, sometimes it refuses to reboot. Power goes on, and I can hear the HD spin up BUT it doesn't contiune to go through the boot/windows load process (no further reading noises from the HD beyond a certain point). The BIOS screen never coimes up - no display whatsoever. The PC will eventually start up of left long enough, but I don't really think the problem is heat related SINCE it is usually cold when this problem occurs.

I have checked that all cards are well seated.

This problem occurred and has persisted since an MB upgrade. Sounds like a pretty close match to your problem.

22-08-2002, 11:43 AM
In my case, the HDD doesn't even spin. The computer doesn't go thru the usual boot cycle. And I've even tried leaving it along for a period of time but still no action.
I'm sure the CPU can't be fried because I've had the case off all day while playing around with my HDDs. And I do use an electrostatic wrist band with the PSU connected to the powerpoint so I'm sure I can't really blame static electricity for frying the chips (though it still is a remote possiblity I guess).

So I'm completely stumped for once.

22-08-2002, 12:27 PM
if the cpu was fried i doubt anything would be working. it still could be PSU (low voltage on one of the rails). it could be just a dead drive. try it without the ide cable plugged in.

basic fault finding required. strip it down to the basics and see if it will produse anything on screen. then add componant back in one at a time untill it faults.

note- make sure the monitor does work (been caught out by a faulty monitor cable before)

22-08-2002, 12:42 PM
hey btong

i had the same prob wen i put my pc together, the pc would boot up, but no hardware would go. in my case it was the Mobo, there was a fried chip on board, the mobo wasn't letting any power fo to any hardware. if you have a volt-0-metre, stick the two needles into the power leads that click into the hdd, and the power outage should hover just over 12v. and if the in which you have to insert these needles though.
hope this helped.

22-08-2002, 12:45 PM
> hey btong
> and if the
> in which you have to insert these needles though.
> hope this helped.

screwed that up. heres wot it should say.

and if the voltage hovers around 11.8v. u should be a bit worried. theres a special sequence u should insert the volt-o-metre needles so just a bit of caution is needed.