Downgrade the Ram or upgrade the Motherboard?

I think I figured out the reason the ram has been giving me issues. (See 4Gb+4Gb = Firefox crash).
I got my purple fans today and realized that there was spots on the motherboard that looked like the smaller plugs on the fans. (Yes I'm still a n00b). Google led me to a page that told me about my motherboard. I found out that my motherboard only takes DDR2 ram. And I have DDR3 in there right now. I think this solves my issue as to why my computer crashes when I try to put 8GB of ram in it....

So do I upgrade the motherboard or downgrade the ram?


(It doesn't want to let me post this URL to the motherboard specs)
Asus P5BV-C

you can still buy ddr2 memory, there are still systems being released that only support ddr2 memory so it isn't going away any time soon