I have 8 gb of ddr2-667 on my Asus Maximus Formula running at the standard 333 Mhz. I have the ram timmings set to 5-5-5-15. The RAM is generic K-Byte 2GB modules but they have the Micron D9 chips. I had these modules in my old gigabyte board running at 4-4-3-9 with no problems at all. After exchanging the motherboard for the Asus (and reading the horror stories about this board and its picky ram requriements), i left the timmings at 5-5-5-15. Will i notice any speed increase, just doing "normal" work in going to a 4-4-4-12 timming
So far the system is very stable at 5-5-5-15
Normal work... not unless a couple of nanoseconds is of any use to you... then again 'normal' work is a pretty vague statement, I'm just going to assume you mean word processing, web browsing, stuff like that
Not worth it. Memory doesn't bottleneck systems like it did a few years ago. That means diminishing returns for additional ram, faster ram, and tighter timings.