as above , when it does boot it works fine , i can see the bios everything ok power settings graphics and memory all a ok . but after a shut down i cannot boot . i have tested monitor keyboard and mouse .
when i turn on i dont get to the post screen and no beep ,
fan goes round cd opens all lights are on ,just no boot screen .


the above is what i sent to acer ,not wanting to admit that i have also change psu used different ram used a graphics card instead of the on board tested with another hdd tested with another dvd reseated cpu and repasted .

and asabove when it does boot 1 in 20 times its fine .

any ideas .

i did have an acer tower once where they sent me a bios update and a couple of keyboard shortcuts to upgrade the bios
any one had the same with an M1640 .
thanks in advance Paul

I once fixed exactly the same PC for my Uncle's girlfriend.

Turned out the motherboard was forked, and I ended up going and getting them a new motherboard. I never found out what was wrong, but I did find out that flashing the BIOS made it worse.

I wonder if you tried reflowing the solder on the NB/SB using a hot air gun/really hot hairdryer. Sometimes because they use lead free solder now, it doesn't flex with the temperature and can break away.

Just a wild guess, but it could work.

Good luck!

My first thought was RAM, but since you checked that and all the other usual suspects I agree with Bally199 and suspect motherboard issues.