Computer no post no beep codes


Recently i was packing up the desktop for transportation reasons and by a slip of hand, the desktop hit the floor from about 4 inches, the place of impact is the lower back end where the psu is located. Immediately, i tested the system to see if it works. The system powers on, but the system wont post and it wont beep. all the fans were about to run ( case fans, cpu fans, gpu fans). I unseated both both of the rams, and there weren't any beeps. I then unseated the gpu, and still there was no post and no beep code. Also there is no video output. I have no yet unseat and reseat the cpu. Please help me diagnose my problem, also the system has been working perfectly fine until i dropped it.

system specs:
amd phenom II x6 1090T with the cooler master hyper 212 plus.
g skill sniper series ram 8 gb
asus m4A870T evo
corsair 750w psu
sapphire radeon 6950 dirt 3 edition

i haven't tried reseating the cmos battery , or the resetting the cmos with the jumpers. What are the odds of a broken psu or mobo from that drop...?
9 answers Last reply
More about computer post beep codes
  1. You may well have shaken something loose. First, check all your connections etc. Take the whole thing apart and carefully put it back together. Follow this if you're not certain you've done everything:

    If you've got everything seated nicely and you're still not getting anything, you'll have to start searching for the culprit, the broken part. This will be far, far easier if you can get access to compatible parts from another PC. Do you have another home build in your house? Do you have a friend that'd be willing to lend you a PSU, or to let you swap in your CPU for theirs? You have to try each part with other parts that are known to be working to eliminate it as the problem.
    I think we can ignore the RAM and CPU as possible broken parts, though they may be loose, but everything else is suspect.
  2. i have a friend at college who has a desktop, i cant test my cpu as he is using an intel system however i can test everything else, and i plan on doing that once i return to college later tonight. First thing i will try is reassembling everything.
  3. You should try each of your parts with their system. Try RAM, then HDD, then PSU, in order of easiness. If all of those appear to work, then I'm afraid you've probably done in your motherboard.
  4. You can get a headstart with your troubleshooting.

    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 no luck, continue.

    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, 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 (standby power supply): 5 volts always on. The green wire should also have 5 volts on it. It should go to 0 volts when you press the case power button (this is also a good way to test the power switch and the associated wiring), then back to 5 volts when you release the case power switch. 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.
  5. ah i forgot to update. Thanks for all your helps. It turns out that due to the large heatsink of the cooler master hyper 212, it dislodged the cpu. reseated the cpu and everything is now A-OK~.
  6. Excellent.
  7. The Hyper-212 dislodged your CPU? makes you realise how much worse it could be if you used the Silver Arrow or Noctua NH-D14...!!!
  8. Truly what an nightmare that would have been had i decided to get those heatsinks.
Ask a new question

Read More

Homebuilt Systems