Gigabyte iDNA motherboard

I have a Gygabyte GA-K8N51GMF-9 (iDNA) motherboard that I have installed an AMD 3400+ CPU on it.
It also has a GeForce 6100 onboard graphic card that has been connected to one monitor. It uses 128M shared memory. Also I have a separate GeForce 8600 graphic card that has been connected to another monitor. I need much RAM because I have many memory hungry programs that I have to run simultaneously like Altium Designer, AutoCad, many big PDF files,…
In motherboard catalog it has been said that the motherboard supports up to 4 Gigabyte of DDR RAM. It has said that for using dual channel technology all RAM modules should be the same brand and the same capacity .I have followed manual instruction one by one and I tried to install 4 G(4 identical module) kingstone RAM speed 400 on it but after turning on the computer halts(no screen, no error beep, no POST beep), it just halts! When I install 3G of RAM computer works without problem(I’m sending this post with the computer that has 3G RAM). If I install a 512MB RAM in module 4 instead of 1G computer goes one step further but again it halts, it means that the POST beep is being heard but right after POST beep computer halts.