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Computer wont start

Last response: in CPUs
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July 30, 2010 12:15:52 AM

Recently i cleaned out my computer blew out some dust etc. When I went to start the computer it would continuously beep and the fan would blow at full speed with no video. I wanted to be sure I didn't knock anything loose so I removed the power supply, ram and video card and made sure everything is connected correctly. I also tried disconnecting the hard drive and booting up and still nothing screen was just blacked out. Also I tried using the graphics card on the motherboard to see if it would boot then. I was wondering if it could be i ruined the cpu and or the motherboard I'm at a loss at this point.
Also now the computer will start to start up then kick off then just blasts the fans around 5 seconds later

Intel core 2 quad q 6600
4 gigs of ram
Antec 650w psi
Radeon 5770

More about : computer wont start

a b à CPUs
July 30, 2010 5:46:58 AM

Did you connect all the power connections?
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a c 172 à CPUs
July 30, 2010 4:14:10 PM

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
yes? I mean work through, not just read over it.

The checklist at the beginning should isolate your problem. It's probably cabling somewhere. But if not, on to serious troubleshooting ...

Breadboard - that will isolate any kind of case problem.
http://www.tomshardware.com/forum/262730-31-breadboardi...

The breadboarding thread has a paragraph about how to build and test a PC in stages.

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:
http://www.cwc-group.com/casp.html

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to.

You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU.

At this point, you can sort of check the PSU. Try to borrow a known good PSU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card. Silence or long single beeps indicate a problem with the memory.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step.
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