Topic: only the cpu fan turns on? HELP!

[lucasdeltoro]

I was re-installing Windows on 2 computers at once (in different rooms) and when I came back to my AMD Thunderbird, it was off and there was the light smell of smoke in the room... the computer won't turn back on so I left it off and unhooked the power.

Next day when I try to turn it on the CPU fan starts up (at a slower rate maybe) but nothing else does. The CPU fan is plugged into the Motherboard... so from this I deduce that the power supply must be ok (plus it's fairly new).

SO - is the problem my MotherBoard or the CPU?

The system's components were all being used before, this was just a re-install of windows. I don't have LED lights to tell me what's up and it's not returning any boot screen or error information and no beeps when I press the power button... only the CPU fan starts up.

I would think that if the MB was burnt that it wouldn't pass power through to the CPU fan... and without a CPU, you won't even get a boot cycle, right? That's why I don't think the problem is with the MB - I think it's the CPU that has burnt out.

Does this logic make sense to anyone who really knows? Please help me!!!


THANx
-dT

[ketamininja]

Sometimes a faulty (burned out, in this case) peripheral like an internal modem card can stop the pc from starting.

Strip your pc down to:

cpu + heatsink/fan
memory
gfx card

- thats right, disconnect all PCI cards, and IDE ribbons and power cables - it could be your CD-ROM drive thats dead, and sending invalid data down the ribbon, or taking all the power from the PSU.

If you PC starts from here, plug things back in until it doesn't work.

If it still don't work at this stripped down level, then remove the GFX card, and test - listen for BEEPS, if none then remove the memory. Hopefully you should get beeps. When the beeps occur AFTER the removal of an item, that item if faulty.

If there still isn't any beeps, then the MB has fried somewhere, sorry.

In any case, you will have to replace at least one item.

[lucasdeltoro]

Thanks for the reply. I took away everything except the CPU/FAN, Powersupply, RAM, Video Card and turned it on - nothing except the fan on the CPU worked for a few seconds. Removed the Video Card - same result - no beeps on any of this... at last I removed the ram and now the CPU fan turns on and seems to stay on at normal operating speed but nothing else happens. No beeps, no lights - nothing.

So is the problem my CPU or my MB? I have had the keyboard (PS2) plugged into the comp when I plugged in the power supply and the LEDs on that light up when the computer's PS is plugged into the wall (but before I turn the PC on). This makes me think that the power must at least be moving through the MB, right?

Thanks again for the help...  

[ketamininja]

well, it could be that the memory is the problem... no beeps might mean your pc speaker is plugged incorrectly... or that your mobo settings are strange... who knows exactly?

I would suggest clearing the BIOS before trying again, but put the GFX in, and try one memory module if you have two, or another memory stick completely if you have one..... from your other pc.

if still no joy, then its your CPU or mainboard. Its hard to tell which. The jumper or clock settings may be wrong, but likely to be hardware issue.

Since you have two pc's hopefully same socket mobo, take the (maybe) faulty CPU and stick it in the working mobo to test that CPU. Then you will know whats wrong.

Its good when you have two pc's  

[Sandra]

Sounds like the ram is either faulty or not connecting properly.
Try replacing it making sure that its securely seated and see if the fan still runs and at that point you should hopefully be able to get into the bios.
If it still wont run the fan have you got some different ram that you could try it with ?

[lucasdeltoro]

aight thanks yall... I tried what ketamininja said and cleared the bios, then put in my graphics card and 1 of the 2 memory sticks I was using before, just like you said. still no beeps or lights, but the CPU fan worked.

my other computer is a P4 so I can't swap the cpu, right? I could swap the ram - the two chips in the problem AMD are SDRAM and I have a stick of DDR that I could put on that MB (it supports both)... but even if the SDRAM I've been using is faulty, wouldn't I at least get lights and beeps? I'm getting nothing anywhere except that fan on the cpu and the lights on the keyboard when the computer is plugged into the wall... is that an indication that the MB is ok maybe?

thanks again for the help - and yes, having two PC's does rock... except when you're the only one in the household who's fixes them.

[Sandra]

It is unusual to get no lights or beeps but I think its still probably a ram issue, maybe one stick burned open circuit and the other somehow burned close circuit then that would make them both faulty but maybe only one stopped the fan spining up, probably the short circuited one and the other one which allows the fan to work then stops the bios loading fully to generate the beeps  

[lucasdeltoro]

Thanks for the help Sandra... but I tried another stick of SDRAM that I had around here (from an old computer which I tested first and the ram is still good) and that did the same thing as the other sticks of ram I had in there before... nothing. The CPU fan went around a few times and then nothing.

any further help is much appreciated... thank you so much.

[ketamininja]

hmmmn, well unless there is a jumper that dictates which memory slot you are using SDRAM/DDR that is set incorrectly.... and since your using one AMD and one P4, then it could be either the CPU or mainboard.

really, the only way I can think to test is if you get yourself another AMD chip  

[Sandra]

When you cleared the CMOS you did replace the jumper back in the normal run position did you ?

[Adept]

If it were a RAM problem, POST would beep to tell of the problem

It is more likely that the CPU or motherboard is fried. It is difficult to tell which it is, without either trying the CPU in another board or trying the board with another CPU.