You have a few options open to you if you wish to continue with the ram;
1 Inspect the CPU and see if some of the pins are bent or missing.
2 Check the memory slots for contaminants, bits of dirt basically which might be causing your memory not to be picked up
3 Change CPU and see if that helps
4 Change motherboard and see if that helps
5 See if you can borrow a buddies system that is know to work to test all your components.
Number 5 is the best of the options I listed. I have used the new RipjawX 2400 kit on some of my AMD systems and I did not have great success with all the processors. Older RAM from two or more years back worked better on my systems.
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