DDR Memory - PC2400@CAS 2.0 vs PC3200@CAS2.5

[Randy_77]

I'm confused by DDR memory specifications/sales pitches. Some vendors seem to make a "big deal" out of "CAS2.0 Certified", and charge a significant premium price over standard CAS2.5 for the same PCnn00 speed.
If I plan to run my 266mHz AthlonXP 2200+ on an nForce2 motherboard at a system speed of about 140-148mHz (versus 133mHz base - marginal overclocking), why can't I just get PC3200 spec memory (for a couple of dollars more per stick) and run it at CAS2.0 rather than spend a LOT more for PC2100 or PC2400 "certified" for CAS2.0?

[Budfred]

Why are you posting the same exact message in the same forum in 2 separate threads. It is not necessary and it is considered to be a rude waste of resources around here.

http://www.pcguide.com/vb/showthread.php?s=&threadid=21602

[saphalline]

The simple answer to your question is that they charge more because they can! :rolleyes:

What I've found is that if you buy good name-brand RAM (Micron/Crucial, Corsair, Geil, Hyundai, etc) rated for CAS 2.5, you can run it no problem at CAS 2. Where CAS 2 becomes important is during overclocking when that extra 0.5 CAS rating can mean the difference between stable RAM and a crashed system.

However, as you state, it's more cost effective (and smarter) to just buy faster RAM with a slower CAS setting, and then run it at CAS 2 anyway. :D

In fact, my old Asus A7V266-E motherboard ran my Crucial CAS 2.5 RAM at CAS 2 automatically! :p I never touched the memory settings, and I actually just let the RAM run by SPD (meaning auto-config). So the whole time, from first boot-up until I upgraded, my RAM was being run out-of-spec by my aggressive mobo! I thought that was just hilarious when I found that out.

In retrospect that was probably a good thing as my first stick of RAM turned out to be bad, and without my mobo to stress my RAM, I don't think I would have found out until several months later. I learned my lesson - always test your RAM!