No post/video

randomgerbil

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Aug 16, 2011
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Hi, My computer will not post, and displays no video

I've always had a memory issue with this machine, and experienced boot problems before. However, this time a cmos reset, which sorted out the problem before, isn't working.

At the moment, the CPU, HSF mobo and PSU are breadboarded. On power on the phase LEDs light up, and the system speaker sounds long beeps (video card problem, according to my manual) The components then power off, then the system reboots. repeat ad infinitum. The CMOS battery is not installed at the moment. There are no screws or other materials on the motherboard with could cause a short.

The aforementioned memory problem is that only one stick is 'enabled' in the BIOS, and there is no way to change it so both are enabled.

spec:
https://secure.scan.co.uk/aspnet/Shop/SavedBasket/SavedBaskets.aspx?Id=b1fc14d0-086e-4307-94f7-7d78fe94d9f9#BasketDetails
OS is win 7 64bit, upgraded from 32bit vista.

The system was built in October, 2010

So far, I've troubleshooted using this guide:http://www.tomshardware.co.uk/forum/261145-13-perform-steps-posting-boot-video-problems
apart from testing my PSU with a multimeter.

Thanks in advance for any help
 

nadim615

Distinguished
May 28, 2010
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18,810
Are you sure that your computer can RUN windows 7 64 bit? Also, I'm pretty sure that you need 2GB of RAM minimum to run windows 7 64 bit, so if you dont have that then I dont think it will work... Also if you have too much RAM installed on your computer, this can cause a problem too. Ex: your computer can hold 6gb, but you have 8gb installed. Could cause problems... Too much RAM installed has been known to cause boot problems and screen flashing...

Here are the minimum specs to run windows 7 64 bit, for some reason I needed to make an account on that site that you linked me too, and I didnt want to go make another random account :p

http://windows.microsoft.com/en-CA/windows7/products/system-requirements

Make sure you have what it says for 64 bit!
 
When you are asking for help, always start off with the system specifications. Or post a link that works. :)

Breadboard and build and test in sections.

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.
http://www.tomshardware.com/forum/262730-31-breadboarding

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. 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=youtube_gdata

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.