I have an ASUS P5V800 motherboard. I have been having problems with the computer hanging at random times during start up. Sometimes it hangs before the mem test, sometimes during hard drive detect, sometimes it can't detect my hard drive at all(SATA Maxtor 100G) and sometimes it hangs at mass storage detection. I have taken one of the two 512M RAM chips that I thought might be a problem but still having problem. I am usually able to get it to boot up by restarting the computer a numbner of times. Any advice.
Have you tried cleaning the connections and as well as the motherboard? Based on my experience, dust, especially moist dust that has build up inside the CPU tower can cause malfunctions. What i usually do is i dismantle the CPU tower and clean the components inside with soft-brissled paint brush like heat sink and fan, motherboard, graphics card, etc. When in come to the RAM i clean the pins with pencil eraser like shown in the image below. and re-assembling them again. hope this helps