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System won't start- what's wrong?

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  • Homebuilt
  • Systems
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September 21, 2010 5:59:57 AM

I finally tried to build my first computer today with the parts listed below, but when I try to turn on the computer, nothing happens. I disconnected all the peripherals from the PSU to eliminate that as a problem, but it still won't start. When I initially flip the switch for the PSU, the lights on my keyboard (Caps lock and the like) flash for a second, but then when I hit the power button on the case, it doesn't turn on. The PSU never makes a noise and the fan doesn't move.

I thought this might be because I only used 2 out of the 3 cables that you can't detach from the PSU (the website says that all "non-vital" cables are detachable, so maybe I need to use all 3 of these "vital" cables?). I used the 8 pin CPU connector and the 24 pin main power connector, but am not using the 4 pin CPU connector since there is nowhere on the motherboard to put it.

Do the lights on the keyboard mean the PSU works and I'm just doing something wrong or is the PSU dead? Or is it something else entirely, like the motherboard being dead? Thanks.

Build:

ASRock 770 Extreme3
OCZ 700W ModXStream Pro
AMD Athlon II 640
HIS Radeon 5770
OCZ Special Ops Edition Low Voltage RAM, 1600 Mhz, 2x2 GB
Antec 200 Case

More about : system start wrong

a b B Homebuilt system
September 21, 2010 6:41:41 AM

The lights indicate that there is life in the PSU. Make sure that your RAM DIMMS are installed in the white slots. Make sure that your video card has the power connectors in place and make sure that your motherboard isnt earthing out on the case.
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a c 122 B Homebuilt system
September 21, 2010 7:10:47 AM

Using the 4 and 8 pin CPU power cables is usually an either-or thing. You use one or the other. That's why you do not find an extra 4 pion connector on the motherboard.

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

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

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case.

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. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. 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 the system beeps:
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. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
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a c 122 B Homebuilt system
September 21, 2010 7:14:21 AM

Wamphryi said:
The lights indicate that there is life in the PSU.

Not necessarily true. Those are powered from the small standby power supply inside the PSU.

Using the 4 and 8 pin CPU power cables is usually an either-or thing. You use one or the other. That's why you do not find an extra 4 pion connector on the motherboard.

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/ [...] t-problems
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/ [...] adboarding

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case.

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. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. 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=5FW [...] tube_gdata

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 the system beeps:
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.

Oops. :( 
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September 21, 2010 2:41:53 PM

thanks for the quick answer- sorry for not looking through that checklist earlier. I'm in the process of breadboarding right now, and have gotten the PSU fan and CPU fans to start up by shorting the power switch on the motherboard. However, I haven't heard any beeps anywhere. After spending half an hour looking through the ASRock website for an answer as to whether this mobo has speakers or at least to find a tech support phone number, I figured I would see if anyone here happens to know if the ASRock 770 Extreme3 has an onboard speaker. Thanks.
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September 28, 2010 12:15:40 AM

Best answer selected by oddtodd.
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