My system turns on but fails to put out any video signal. I built it a little over two years ago. The components are:
Arctic Freezer Pro 7 Rev.2 cpu cooler
Antec Solo case
WD6401AALS 640 MB HDD
ASUS Radeon HD 4770
Corsair XM2 DDR2 800 4 GB (2x2GB)
OCZ ModXStream Pro 600W Modular PSU
The pc refused to boot up. The lights, case fans, and psu come on but the cpu fan does not turn. I tried a fan from another pc and that fan wouldn't turn on either. I also tried plugging the fan into the MB system fan header and it still did not work. I'm thinking the motherboard is DOA and ordered a replacement board (MSI G41M4-F LGA 775 Intel G41 Micro ATX) , but I wanted to get someone else's opinion before I take everything out of the case. Any advice would be appreciated.
Your problem could be almost anything, including the PSU.
The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.
I have tested the following beep patterns on Gigabyte (P35 & P45, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.
Disconnect and unplug everything from the motherboard except the main and CPU power cables, CPU & HSF, and the system speaker. You want to disconnect the case wiring because something might have shorted and prevented your system from booting (unlikely, but it has happened).
If you do not have a case speaker, you really, REALLY need one.
You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. Working from the back of the main power plug, you can also momentarily short the green wire to one of the adjacent black wires using a paperclip. 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.
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.