For a number of months on and off, occasionally the system would not start up with no beeps and nothing on the screen. After a few reset attempts, it would come good, so I had to leave it as it would then work fine which is unsuitable for troubleshooting.
Anyway, today it was in standby from last night and would not start at all. So, I ended up disconnecting all peripherals except the CPU, Memory and Video card. Nothing would happen, no beep, no video, nothing. Swapping the CPU, memory and video cards made no difference, so I ended up installing the HDD into another system and reconfiguring it to suit the different motherboard. This gave me some time to research and test.
Connecting the information that I found here with the support pages at ASUS, I removed the battery and cleared the CMOS, but this did not seem to make any difference. As this second hand system is a few years old, While I had the battery out I checked it with a multimeter and found that it had a reading of 0.8mA. I had a used one which had ~3.0mA, so I inserted into the battery slot.
However, the system would not start or beep, but after a couple of resets and some more thinking time, the screen lit up and I was able to get into CMOS. The thinking time would have been between 30 and 60 seconds, possibly more. During some of my testing with parameters, after save and exit, I got a warning about CMOS checksum failure requiring me to install and insert a floppy disk. I cleared this with another CMOS reset and reconfigured the CMOS again. Subsequent restarts still work, but I will check it again in the morning to see that it is alright after some time off.
The important thing to note here is that changing the settings in CMOS for the memory and fan operation etc, get invoked after save and exit, so this is something to consider when having memory issues requiring CMOS clearance. Additionally, there is quite a lag time before the screen lights up when there is a problem with the CMOS settings for the memory, so patience is the key.
Furthermore, get a cheap multimeter to check your batteries so that you can eliminate these problems before they occur, during your regular preventative maintenance.
Edited by Repete456, 10 November 2009 - 01:51 AM.