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New PC troubleshooting and general questions.

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Last response: in Systems
January 14, 2011 6:01:05 AM

Hello so I'm having an issue with a new pc i'm building and do not know what else to try so here are my specs to start off with:

Intel i7-960
Intel DX58SO (mobo)
Corsair 3x2GB DDR3 1600
HIS IceQ 4670 1gb
WD500GB Caviar Green
Asus CD/DVD Burner
Antec 300

So for simplicities reason I have disconnected the hard drive and cd drive, also have taken the mobo, cpu, ram, video card, and psu out of the case. All of which should eliminate a whole slough of problems. Basically what happens is that I press the power button on the motherboard and nothing happens at all I do not get video output...

The graphics card works for sure I tested it on another pc, the card has no onboard additional power supply, it recognizes the ram because if I remove the ram it beeps from POST (1.does the fact that is posts mean that I have a working motherboard or no?) Also the DX58SO has two seperate auxillary ports one is a molex connector the other a SATA connector which are used to "power a pcie card with more than 75W" and I have tried every combination of having one or the other or both or none plugged in. I have tried changing the CMOS jumper back and forth position wise and removing the CMOS battery and putting it back in.

2. What do you suggest I try now?

More about : troubleshooting general questions

a c 121 B Homebuilt system
January 14, 2011 6:37:47 AM

#1. It suggests that you have a working CPU and, at least, a partially working motherboard.

Leave the two aux power ports on the motherboard alone. Do not connect anything to them. Use the PSU cables to power the video card.

#2. Work systematically through our standard checklist and troubleshooting thread:
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, but they all use a single short beep for a successful POST.

Breadboard - that will help isolate any kind of case problem you might have.

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 once you are finished.

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.

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

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, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

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.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

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.