[DougMacp]

Hi, I'm about to but a new motherboard and the specs say it takes dual-channel DDR3 memory. Will it be backwards-compatible? I'm hoping to use DDR2 mem as these RAM appear quite a bit cheaper at the moment. Thanks all,

[Compiler]

No.

You'll need to buy a DDR2 motherboard to use DDR2 memory. Select a different board.

Core2Duo and AMD chips don't perform much better with DDR3 (in the real world).

[BG-0]

No, you can't use anything else than it specifies as compatible.
Get a board that has support for DDR2 RAM. If you're not getting an i7 CPU, DDR3 RAM will not be any good for you.

Could you describe your plans a bit more in detail?

Harr, dragging one minute behind

[DougMacp]

Thanks for your suggestions Guys, Building my own and just didn't want it to get out-of-date too quickly. I've saved a for a while and will have an ATI Radeon 4890 graphics card and AMD 2 Phenom x 4 (AM3). I'm just wary of going for DDR2 now, then a few years down the road if I want to add more memory they have become expensive as DDR3 would be the norm by them. (e.g .DDR2 for my old Dell is very cheap but DDR(1) ram for my VERY old eMachine are expensive as they are now so old. What do you think?

[Compiler]

Well... DDR3 is approaching DDR2 prices. A year ago, 4GB of DDR3 was about $200~300.

Nowadays, 4GB is about $70~120. An AM3 motherboard is going to cost about $20 more than an AM2+ (DDR2) version.

Then when it comes to DDR3, you really want to get the lowest latency you can get... which is 6... 7 is okay. 1333mhz is fine.

DDR3 - latency 7: http://www.newegg.com/Product/Produc...e=&srchInDesc=

DDR3 - latency 8: http://www.newegg.com/Product/Produc...e=&srchInDesc=

DDR3 - Latency 6: http://www.newegg.com/Product/Produc...e=&srchInDesc=

Looking at the scoring... as the latency gets lower, the issues tends to go up - typical of tight timings. At CAS 8, the GEIL are scoring high.. compared to CAS 6 & 7. Also look at the DDR3 compatibility list from the Mobo website and the requirements. Such as speed and voltage.

Going with DDR2 with an AMD... either 800mhz for flexibility or 1066 for a tad better performance. I'd say, 800mhz. DDR2 800Mhz is about $40~50.
http://www.newegg.com/Product/Produc...e=&srchInDesc=

In a few years... you'll want a new motherboard anyway. In mid/late 2010 - Motherboards will be USB3, PCIe3, SATA3... The first boards will be expensive.

DON'T buy the 4890... Especially since your STILL saving today.
The 5850 & 5870 cards will be out any week now... cost less and twice as fast.

[Compiler]

Add this part.

If you buy an AMD mobo in the next 1~4 weeks, most have onboard video. The 785 and 790 chipsets are very good. $80~120. You can use the computer a bit before the DX11 cards come out and Windows7.

Windows7 isn't like Vista... 2GB for Win7 is enough for most people. Vista needs at least 4GB to be usable. I'd take a 1GB Win7 computer over a 4GB Vista any day.
Of course, going 4GB - you're back to using a 64bit OS in order to use ALL the RAM.

So for today (0~3 or so weeks) The overall price difference is $60~75 to go with DDR3. If you need more memory in 1-2 years from now, yes DDR3 will cost less than DDR2. But you may want SATA3 and USB3 - because USB2 isn't cutting it for backup drives and SATA2 isn't cutting it for SSD drives.

[DougMacp]

Thanks for your thorough replies,Compiler. A lot to think about and I'm learning quickly (or at least I'm trying to!). I always get excellent help on this site.

Best wishes.