An IBM 6790KBM Computer Constantly Restarts on Boot

An IBM 6790KBM computer restarts after showing the Win XP bootscreen and also briefly shows the memory dump error or commonly called the Blue Screen of Death or the BSOD. It was handed to us but the system unit was already been tried to be fixed by another technician. We then asked the computer technician on what problems did he encounter and the fixes he has done. The computer technician said that he was suspecting the following components to be defective and has taken some actions or fixes.

a. RAM or its DIMM Slots
- He checked each of the RAMs in binary method. One RAM after the other tried on each DIMM slot.

b. Video Card
- The Video Card has also been suspected because it shows trashy video sometimes.

c. Motherboard
- The Computer technician said that he checked and tested the RAMs and the Video Card on another system and were just working fine. So he suspected that the motherboard is failing.

d. The Processor???
- Yup, he suspected the processor. That could be quite impossible considering that the computer has display and bios configuration could be accessed. What must he be thinking then.

e. The Power Supply Unit (PSU)
- I asked the technician earlier before I accepted this job that did he check the power supply. He said no, because everything seems fine and working.

Those were the Computer Technician's suspicion and I need to check it myself rather than resting my computer troubleshooting skills on his observations.

Date Fixed : August 27, 2010

Problem : IBM 6790-KBM computer will restart after showing the win xp boot screen and briefly stalls showing the memory dump error or the Blue Screen of Death or BSOD then restarts.

Owner : I dont know. The Computer Technician handed it to me.
Motherboard : IBM 6790KBM 1.5 Ghz Processor
Operating System : Win XP SP 2

Technician : Drokz


- Computer needs to be fixed in a day


- Intermittent restarts on boot up attempt
- Has power, has video, shows POST, boot attempts then crashes and restarts.


***** please turn off the avr and unplugged the power cord if you'll replace and test any peripheral in a system *****

- Since it has display and shows the POST, we should check the RAMs if they are working right. To do this, disconnect all the data cables, the power connectors to the drive and the peripheral cards.

- The computer is installed with two RAMs so we need to check each RAM on every DIMM slot. After swapping each of the RAMs on the DIMM slots, we found out that DIMM slot 1 and the other RAM is defective. How was it determined? On POST. The Computer boots up so slow when the other RAM is inserted. And also if the good RAM is inserted in DIMM slot 1, it stalls the computer on POST. Use the binary method in testing the RAM.

- We already determined that one of the RAMs and DIMM slot 1 are defective and been eliminated (RAM removed, DIMM slot unused), it did not solve the problem at all. So its time to check the disconnected peripheral if which is failing. So we started checking with the hard drive.

- We connected the Hard Disk Drive and tried booting up the system. It looked good at first because the POST was relatively faster. But on XP's boot up screen, it still stalled and briefly show BSOD then restarted. We then assumed that this could be an OS problem but I suggested that the PSU must be checked.

- So we opened the PSU and found no physical evidence of defective components. But our suspicion on the PSU still persisted so we tried another good PSU and the system booted up successfully! We finally got the system running well. The tested good PSU was rated at 400 W, could it be that the older PSU can't fully sustain the power that the IBM consumes? The system is now running fine after some RAM , cable and connector checks.


- The IBM 6790KBM computer had a failing DIMM slot 1 and one of the RAMs is found to be defective. But removing the defective RAM and leaving the DIMM slot 1 unused didn't solve the problem but significantly made the computer run better.

- The PSU was then founded out to cause the boot-restart problem. This intermittent and stubborn problem was caused by the Power Supply Unit and has been replaced. The system is now up and running fine.

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