CPU fan spins, but no motherboard beep

[gooberguy]

i recently just unhooked my video card to clean the fan. upon returning everything when i press the power button on the computer there is no beep or video signal

so i thought i did something to the video card , so i took it out (there is no onboard video) figuring i could listen for the windows sound when it booted but nope.

also i noticed if i press the power button while the computer is "on" (i see the cpu fan spin and i think i can hear the HD spin, the computer instantly turns off, telling me that windows isnt even remotley loading

with my video card still removed i took out both ram sticks, when i boot with no ram or video card, i get a short beeeeep. not instant but stretched out a bit

i'm not sure what to do =\

[minidv2dvd]

put back the ram and vid card. make sure they are firmly seated. take out all other cards and remove the power connections from all drives. you should have m.b., cpu, ram, and video card only connected. make sure all their power plugs are in. see if it will boot to bios screen. if not short the clear bios pin or take out the little flat battery on the motherboard for a few minutes. try again. if not you may need to swap out the powersupply and try a different one. if it still won't boot at all with no beeps the motherboard or cpu is most likely dead.

[TBoneit]

The Motherboard will do beeps for no video or no memory so tells me it isn't totally dead.

If you can try another power supply.
Try unplugging all the drive's data and power cables.

If you put a floppy cable on wrong it can short out the power supply. most power supplys will turn on and off if they detect a short to protect themselves from damage.

It is also possible that the short detection circuit in the power supply has gone bad causing it to turn off when there is no short or overload.

[gooberguy]

while i try out the steps 2dvd said im curious, would the computer boot all the way to windows without a video card or onboard video?

[gooberguy]

also i dont think the power supply is bad because it keeps the fans on the video card and CPU running until i hit the power button again

[redwudz]

Sort of obvious and you may have checked, but make sure every connector and card is properly seated. I have knocked wires loose when changing cards several times.

Other than that, it does sound like a power supply problem. If you have another video card, I would try that first, though.

I don't think it will boot to Windows without a video card, but how would you know outside of watching the regular flickering of the HD indicator that you see on a normal boot?

One long beep that repeats usually indicates missing or non-functioning RAM, or on some MBs a dead video card. Beeps should happen before the regular BIOS is loaded.

EDIT: The fans run off the 12VDC rail. The CPU has about a 3V rail and the other logic circuits use the 5V rail. There are also a 12VDC and 5VDC negative rail. If any fail you will likely have a non-working computer. Simple test is to substitute the PS.

[gooberguy]

ok just tried a video card i know for sure works, it didnt work

[minidv2dvd]

you might want to test your power supply at this point.
http://forums.extremeoverclocking.com/showthread.php?t=137886

[redwudz]

Then a PS substitute would be my next step. If that fails, may be a MB failure. Hopefully, if the PS is the problem, it didn't damage the MB.

Why any of this would have happened when pulling a video card, no idea. But I would also closely inspect the video card slot, on the off chance there is a bent pin or something obvious there.

[Sartori]

Id concur with above on checking and swapping cables , changing ps then ram . Similarish symptoms/problems Ive had to yours - loose cables , disconnected cpu fan power plug , bad ram stick , blown power supply and the latest was my new ram needed slightly higher voltage in the BIOS and just played possum until I removed it , put in the old memory and then tweaked the BIOS , saved , turned off and swapped (going for an kitchen sink list if it helps) .

When my PS went , it did still light up the lights on the mobo and the cpu fan was spinning but no graphics at all , I suspect the 12v rail went down the pan - so as the above posters have mentioned , my money is also on the PSU . Mine died while I was building my new system adding in the components , I initially thought my new graphics had died but I had a flash of inspiration (and a spare PSU) .

[gooberguy]

you guys were right, put a new power supply in and it started working, thanks!

[redwudz]

Good deal. I've had a failing PS take out the MB and everything but a floppy drive with it when it died.

Many people don't realize the importance of a good PS. Not a good place to save money.

[TBoneit]

My unlucky brother back in the Pentium days had a failed power supply that must have sent AC through the DC lines. The only usable part was the metal case itself. It toasted all the drives, the Mobo, the Video, the memory & addin cards.

The Power supply was my guess too. I've seen many power supplies fail where the fans run etc. If one of the voltages is out nothing works.

FWIW I still believe there is some validity in the weight test for power supplies. For the same wattage PS the heavier one will generally be the better one. Due to larger heatsinks and such.

[redwudz]

My 'favorite' PS failure was when sparks shot out the back of the PS along with a stream of white smoke, accompanied by a loud 'bzzzzzt'. It's fortunate I was there at the time or it might have caused a fire. The AC line shorted internally through one of the transformers to ground, bypassing the input fuse. The wire then melted in two. This took out the MB and the CPU, but the RAM and drives survived.

I've had maybe five PS failures over the years, most were quiet. One I caused myself by shorting out a HDD Molex plug to ground. I should have shut down the PC before moving wires around. That was the only time a quality PS failed. The others were cheap PS's that came with the cases. I've lost two MBs because of PS failures. The MBs cost 2X to 3X the price of a decent PS, so not good economy on my part at the time.

Weight is one way to judge PS quality. Maybe not the best way, but a good PS is quite a bit heavier than a cheaper one.

[TBoneit]

I suspect that the heavier power supply will also run cooler under load due to the larger heatsinks.

While not the best way if I were shopping and had to have one now for some reason I'd definitely pick the heavier of the my choices for the same wattage PS.

[SingSing]

I am still amazed that those $15 Power Supply can put out 500watt DC and go at least a year before they Karput!

[redwudz]

If you are familiar with some of the older audio amplifier specifications, such as PMP or PMO (Peak Music Power(Output)) or other bogus specs, I can imagine a PS rated at 500W, but only capable of ~200W at best. PMP(O), if I remember correctly, rated the output power when the output was shorted. Maybe OK for a second or two, then the amp melts down or the fuse blows. Some PS's seem to use a similar method for rating.

If you really wanted to explore the PS ratings, you would have to look at the sustained power outputs for each rail, if you can even find that, then compare them to a good, name brand supply. I've ran across a few '500W' PS's that looked a whole lot like a 300W cheap PS. I suspect a label (upgrade) change with a few. A $19.95US 500W PS would be suspect.

I use a simple test most times. If the heat coming out of the PS exhaust fan is similar to a hair blow dryer, or it smells like hot plastic or metal, it's likely not to last too long. The better quality PS's I use normally run at about 70F - 75F exhaust temperature. I use a infrared themometer to check.

JMO, and others will probably differ, but using good quality PS's above 500W seems questionable at times. Some dual SLI cards can use quite a bit of power and may justify this, but for the rest of us, not so sure this is necessary. I have two video servers that have ten hard drives each. One uses SATA and the other PATA drives. Both use a good quality 500W PS, and both PS's run fairly cool.

The servers also have a DVD burner and six case fans each. The servers use about 350W on HDD spin up, then it goes down to about 140W during operation. The video is onboard and rarely used. My other computers draw about 130W during operation. That surprised me. This measured with a AC wattmeter on the AC line going to the PS. The spin up load puts a strain on the PS's, but it's only momentary. Sustained power draws at the 350W level would raise the PS temps. The case temps run about 75F. One of the servers ran for over a year with a 400W PS with no problems, but I upgraded to a better quality 500W.

Most quality PS's now have a efficency rating of 80% or higher, so they should not run very warm. The 20% difference is usually losses due to heat. They use very efficient switching PS configurations. Much better than the older PS's a few years ago.

[gooberguy]

ok another problem.

when i first said the problem was the power supply, i assumed it was because when i took the computer to my friends house and used his power supply, the computer booted, and did the standard beep. i now have installed a new power supply bought from new egg and i'm back to the same problem as before.

=\

[johns0]

Try plugging the computer in a different room.

[TBoneit]

It sounds like you may have left off the 4 pin CPU power connector.

[redwudz]

Strangely enough, I had the same problem a couple of days ago when I changed a CPU from a AMD Phenom quad core to a AMD Brisbane dual core. The hard drive lights would come on and something seem to load for a few seconds, but no BIOS beeps and nothing on the monitor screen. All fans were functioning.

I assumed the new CPU was dead and put back the Phenom and everything worked fine. I then tried the Brisbane in a different motherboard and it's working perfectly.

The problem was the BIOS itself. It was apparently incorrect in either settings or version for the Brisbane. Probably if I had pulled the BIOS battery for a few minutes when the PC was unplugged or reset the BIOS via jumper, it likely would have worked.

I had never ran into this particular problem before.

Long story short, try resetting the BIOS. They can also get corrupted, which somehow could have happened with the video card cleaning.

[gooberguy]

this response is very very late, but just a quick follow up. for some reason, and i dont remember exactly what, but a usb perhiphial was attached, and removing that solved all my problems. nothing else was broken. go figure.

[redwudz]

Some motherboards, apparently by default, will look for the boot files from a USB device and that can lock up a system when they don't find the correct boot files. I've had that happen when I had forgotten I had left a USB thumb drive plugged into a rear USB socket. (And I was about to tear the system apart as I had just changed the CPU and reinstalled the OS and the system locked up. )

I would check your BIOS settings and see if you can disable that feature unless it's something you use. Because it will happen again.

[SingSing]

Good deal. I've had a failing PS take out the MB and everything but a floppy drive with it when it died.

Many people don't realize the importance of a good PS. Not a good place to save money.

That's rare. Normally you lost one of the voltages.

But sounds like your PS lost regulation on 3.3V. It must be those beer that drip into your PS