Hi, Sorry it is not good news, 5 Beeps from the AMI bios, that is definatly a motherboard problem, it is complaining, a quick fix may well be to upgrade your CPU, in this system you are very limited as to what you can put in there CPU wize. In theory you can, MEM and Bios will play a part, as well as heat, can the system handle an upgrade, make sure there will not be problems with Heatsink, this must fit 100%
I would suggest buying or repairing your motherboard.
The upgrade will only be a temp fix. Where as motherboard will last much longer. if you have a CPu knocking about that you can use , it may be worth the effort.