I'm looking to replace my motherboard and CPU with an Athlon64 setup, but can't seem to really decide between Socket 754 and 939.
My goal, is to extend the life of my system by maybe 2-3 years, as I'm very close to graduating from college, so I'm not so bothered by the limited upgrade prospects of the 754 socket. I also want to do this on the cheap, which means recycling as much stuff as I can. To that end I have 1GB in DDR400 RAM in 2x256 and 1x512 configuration, which seems to rule out dual channel memory mode. Would that be a problem with socket 939, which seems to focus mostly on dual channel memory?
The other question I have, has to do with CPU speeds. I've pretty well settled on the 3000+ no matter which socket I get, but the socket 754 3000+ is listed as 200MHz faster than the 939. Is this a result of the 90nm production process, or is it done more in expectation of a dual channel memory configuration making up the difference?
Finally, is there anything else I should be aware of before I go and order parts?
You can run the 939 in single channel mode - you'll lose some performance, but it can be done.
AMD appears to feel that the performance boost of dual channel is enough to overcome a 10% clock speed decrease. In reality I think it's more like 3-5% performance boost, not enough to make up for the 10% clock speed. The 90nm parts do run cooler, but they don't run faster just because they're 90nm.
IMO, 754 is where its at right now for what you described. Better performance, a little lower price, no crippling of the system because you're not using dual channel, etc.
Just to make sure check if your mem is compatible with the mainboard and processor before you buy the board. The on die memory controller in the socket 754 cpu sometimes has trouble with a lot of dimms.
As tweebel said, the memory controller on the s754 boards do not like a lot of sticks of ram. If you use all three, I would bet that your memory bus will be downgraded to 333.
Not that it will make much difference. It will probably still outperform the s939 veriation, at stock speeds.