I would start at the beginning. Set CPU and RAM speed to a lot less than the motherboard clock; i.e. use a low cpu multiplier (Im assuming its possible), and run the ram at 2:1 (or 1:2 which ever makes it slower).
Test the mobo with all your tests, up to 400fsb which should be plenty. Then add in the CPU speed by upping the multiplier. However do this slowly to find slow speeds which actually are stable.
Then assuming all is stable, increase the ram speed. Now that we are testing ram it might be an idea to use memtest.
Im not sure of the bios options on the DS4 but try to increase RAM speed without using exactly 1:1.
Trying to isolate components when overclocking is absolutely critical. In fact any overclocking guide would tell u this.
If you still cant find instability until you have everything up to full speed, then it could be time to try a new PSU.
I have the enermax liberty 500w, I upgraded to it from a enermax 550w; simply because I wanted to have a single 120mm fan that the noise taker series doesnt have. The 550w was for a long time unsurpassed in power delivery Id hope that the 500w can cope with a modern graphics card and CPU.
I have an opteron 146 @ 2.7Ghz and a x1900xt and the rails are absolutely solid as checked with a digital multimeter.
Just checked ** bios screen, its not showing anything particularly important; better to show RAM timings & CPU voltage/ speed settings. 1 thing to note though is that from what Ive read the e4300 has virtualisation tech disabled on chip whereas the e6600 will have it; so u should possibly enable this in bios .