so my im building a new carputer and purchase the m3atx. i have the jumpers set on 5sec off 1 min hardoff. whenever i turn the car off, it would put the computer to sleep. but whenever i turn the car back on, it only get power for 2-3 seconds then shuts off. i have to manually press the power button on the carputer itself to get it to turn on.

so my question is, is this normal or do i have to do some other things to make it work properly?
also i want to set it as 5 second off then 8 hours hardoff, do i have to buy the serial cable to program it?