DDR400 is for S939 motherboards. DDR2-800 is for AM2 motherboards. VERY important difference. DDR2 will not work in a DDR motherboard. And S939 motherboards have a shi*tty upgrade path (non-existant actually).
The performance difference isn't a lot, but regardless you need to get an AM2 (DDR2-800) based motherboard. Upgrading to a S939 (DDR400) motherboard is just plain stupid at this point.
So quit being a cheap bastard and get new RAM. ;-)
I wanna to build with Athlon 64 X2 cpu, and the motherboards mostly offer 2 types or Ram, PC400 and DDR2 800.
I already have 1 gig of PC400 on my current machine, meaning that it will save me about $100 out of buying new ram.
You mean PC-3200 (DDR400), DDR2 800 is PC2-6400.
Just multiply the speed by 8 :wink:
Thats sooo anoying (the speed rating thing not your post lol) I mean why cant they just use the effective speed and leave it at that.... DDR2 800 makes infinatly more sense then PC2-6400 ! The numbers are realavent you can tell "hey its DDR2" PC2-6400 tells me one thing... the marketing department said "Hey people will buy more if the numbers are bigger !!!!11!!1!! OMG"
You might as well go Core 2 Duo if you're going to need DDR2 RAM. The entire Core 2 Duo line is expected to drop in price drastically pretty soon. If you have to go AMD, don't consider S939 as it's now outdated and offers no upgrade path.
[...] And S939 motherboards have a shi*tty upgrade path (non-existant actually).
The performance difference isn't a lot, but regardless you need to get an AM2 (DDR2-800) based motherboard. Upgrading to a S939 (DDR400) motherboard is just plain stupid at this point. [...]
But suppose he rebuilds every 3-5 years like I do. I mean, after 4 years with a 939 or 4 years with an AM2, either way you still end up with an obsolete hard to upgrade system. So upgrade path becomes completely irrelevant if you're keeping it for so long, right?
Would I be better off with a $180 socket 939 CPU and my old PC3200 ram, or an $80 CPU and new DDR2 ram? Is DDR2 ram worth spending $100 less on something else?
A 939 motherboard is not stupid at this point... Its cheaper and offers the same performance as AM2. The ONLY reason to go with AM2 is if you think you're going to upgrade, but in reality its more cost effective to completely rebuild the system every 2-3 years (or more) in which case an AM2 board isn't going to help you. There is almost NO performance difference between ddr2 800 and ddr 400, so if you can get ahold of a 939 board and processor by all means go for it and use your old ram.
If you're considering the extra cash outlay for AM2 it might be worth while looking into a core2duo. Again though, for cost effectiveness, for the OP's applications, your video card will be the most important component (for gaming) so I would stick with a 939 board and the old ram to save some money (at pretty much no loss in performance) if you're willing to have to completely rebuild your system next time.