A PC bought in 2008 would not start at all. Even though the CPU fan was turning nothing appeared on the monitor.
As there was no speaker attached it was not possible to identify the problem by the BIOS beep codes. At this moment there were multiple possibilities of what was the damaged component.
The graphics card was the first suspect. After removing the ASUS HD 6450 graphics card and using the on board one the problem remained.
Next step was checking the ASUS P5N-EM HMDI motherboard for signs of damage.The motherboard LED was on and all capacitors looked ok also the CPU was seated properly and the CPU fan was properly attached. After removing all external connections to the motherboard except the power supply and power button and turning on the PC the problem remained.
Next step was replacing the power supply. No change.
Memory was next to check. This motherboard has 3 memory slots. I checked all possible combinations of the 2 Kingston 2GB DIMM modules including starting without a memory module and the problem persisted.
At that point there was nothing else to check with the current setup. It was necessary to install a speaker in order to hear the BIOS beep codes.
After scavenging one from an ancient Intel PC XT 8088 and installing it there was the first clue to solve the problem one continuous long beep when the memory modules were installed in their normal slot; that meant that the memory was not installed correctly.
The same happened for every combination of memory module and slot except when not installing any memory module when it was one long beep and one short beep which meant memory error.
After scavenging one from an ancient Intel PC XT 8088 and installing it there was the first clue to solve the problem one continuous long beep when the memory modules were installed in their normal slot; that meant that the memory was not installed correctly.
The same happened for every combination of memory module and slot except when not installing any memory module when it was one long beep and one short beep which meant memory error.
At that point it was obvious that the memory modules were damaged. Unfortunately DDR2 ram is very hard to find and really expensive so I had to order a 2nd hand module from Ebay. After a month of waiting to get the package from Hong Kong I installed it and indeed the PC booted without problem except an empty bios battery.
Total cost 5 $ for the memory 4 hours of troubleshooting and one month of waiting for the spare parts to arrive. Best of all the old Kingston memory modules have lifetime warranty and most probably will be replaced by Kingston.
The most important lessons learned are the following :
The most important lessons learned are the following :
- The motherboard speaker is absolutely necessary in order to troubleshoot motherboard problems.
- First thing to do is use a different power supply.
- If the motherboard leds are on, the capacitors look ok, the fans spin and the power button is responsive the motherboard is probably ok.
- Unless overclocked the CPU is the least likely component to be damaged.
- All non essential components must be disconnected in order to be sure that they don't cause the problem. For example a stuck reset button or a short-circuited box fan that is connected to the motherboard will not allow the PC to boot.
- In order for the POST screen to appear on the monitor working memory is needed even when there is a separate graphics card.
- One short beep : System normal
- Two short beeps : CMOS Error
- One long beep and one short beep : Memory error
- One long beep and two short beeps : Graphic card error
- One long beep and three short beeps : AGP error
- One long beep and nine short beeps : Memory Error
- Continuous long beep : Memory not correctly installed
- Continuous short beep : Power supply unit failed
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