DDR2 compatibility questionFollow

I know a lot of people aren't fond of DDR2, but I'm stuck with it either way so I'm going to ask the question.

I want to add another gig of memory to my mobo (not a necessity, just something I want to do). I'm having trouble figuring out exactly what kind of stick I need to buy though. A couple of snippets from my Everest report:

Memory Bus Properties:
Bus Type Dual DDR2 SDRAM
Bus Width 128-bit
Real Clock 200 MHz (DDR)
Effective Clock 400 MHz
Bandwidth 6400 MB/s

[ DIMM1: Samsung M3 78T6553BG0-CCC ]

Memory Module Properties:
Module Name Samsung M3 78T6553BG0-CCC
Serial Number 431036DFh
Module Size 512 MB (1 rows, 4 banks)
Module Type Unbuffered
Memory Type DDR2 SDRAM
Memory Speed DDR2-400 (200 MHz)
Module Width 64 bit
Module Voltage SSTL 1.8
Error Detection Method None
Refresh Rate Reduced (7.8 us)


My DIMM 3 matches DIMM 1 (and there's 2 open DIMMs). So, is this memory PC3200 400mHz or is it something else? I feel like I'm being thrown off by the numbers, particularly "Bandwidth 6400 MB/s". Sooo, oh mighty hardware gurus out there, lend me an ear and let me know what I'm missing here. Thanks in advance.

Indeed, the information you seek is probably in your motherboard manual. If you got one with the machine, which maybe you didn't...

Memory bandwidth is in regards to the amount of data that can be transferred across the memory bus, in your case it's 6.4GB/s and this has no relation to what kind of memory you buy. It's a result of the combination of RAM speed and motherboard/chipset. Higher is better ; ).



Yup, but if your processor only runs on a 400MHz Front Side Bus there's really no reason to go and buy anything faster as the extra clock cycles are wasted.

Your RAM needs to be in matching pairs to acheive it's full performance potential. Buying one 1GB stick would be a big mistake, ideally you'd go out and find two identical 512MB RAM sticks to your first two. Dual channel (Bus Width 128-bit)can be picky when it comes to mixing different types of RAM.

I'm pretty sure that you could fill all your slots on that board without any performance penalties unlike some other platforms on the market. 1GB should be enough for you unless you are working with an application such as Photoshop or any other RAM intensive software however and if I were in your shoes and not doing any of the above i'd save my money.

Edited, Mon Jul 25 23:12:43 2005 by blowfin

Sweet, thanks for the info! So it looks like I'll be paying 60-80 bucks per stick. I already knew I had to install them in pairs, so that's no biggie. Like I said before, I don't NEED 2 gigs of RAM, it's just something I'm looking at doing (I know Windows ME had a problem with more then 1gig, but I'm not aware of XP having that same problem). Bagira, blowfin, Freyr, thanks to all of you, and big RACK for you.