I don't think so, it looks like it supports up to 533MHz only. I suppose you can try overclocking. If you did install the 667MHz, it might drop the speed down to 533MHz. But the worse case scenario, the RAM won't work.
I tried a 1Gb Kingston RAM (667 ofc) on the motherboard and only 512Mb showed up when I started the computer. I turned off "Enable Core 2. CPU overclocking" from BIOS. Then it started up, shows "Memory loading..." and then it´s "Memory 1024000" something. Restarts, loads memory again and shows "Memory 512000" something. Boots up fine. Shows 512Mb.
There is no use when the max is 2Gb, I put in 2Gb, but it shows and runs like 1Gb. My guess is I really have to get DDR2-533.
My daughter has this motherboard running with a single 1 GIG 667 albeit a bit slow but I downloaded the manual for Rev 6.6 which stated that 667 was OK with this board, probably with rev 6.6. How do I find out which rev my daughter's motherboard is as I am a bit hesitant to buy more 667 if this is not going to work. Pls copy me on email@example.com if you can help me.