When i restart my sql server i got cpu load 45% and mem 2% and after 8 hours is going to 90% and ram 3% and after 8 more hours i have cpu load 140% and ram 4% and after that when all user are gone from my forum after midnight ithe database keep the same load and is not going down
Only if i restart it is going down for many hours and then start again to increase all stats....
Make sure you have mysql_close() around the place. Also why is your MaxClients so insanely high? Unless you are running very, very, popular websites I dont think you need MaxClients 1000. Also You want MySQL to eat up ram, if set up properly. So it works off RAM more than your hard drive.
To be perfectly honest it looks like you need someone to optimize your server for you. But first make sure your php scripts are running mysql_close(). See if that helps.
I can think of many things that can lead to this. I'm not sure fiddling with Apache will help with MySQL. Try running a check on all tables in the forum DB if you haven't already and post more info (node, free ram, show full processlist, etc).