Socket 939 and single channel memory - can it be done?

[mbf]

Hi!

I'm looking at upgrading to an Athlon64 solution, but since I'm somewhat strapped for cash (who isn't, these days ) it has to be the most economical upgrade possible. At the moment I have a P4 2.0 Northwood on an ASUS P4B533-E mobo with 768MB DDR266 RAM. Graphics card is a Radeon 9800 and the sound card is a SB Audigy.

With that in mind, I am/was looking at a socket 754 nForce3 250gb mobo (gotta have that hardware firewall!) and an Athlon64 3200+ with 1MB L2 cache so that I can continue to use the rest of my components until it's time for that inevitable major upgrade to PCIe, DDR2 etc.

Anyway, even though socket 754 solutions are quite cheap in their own right, as a platform it probably won't last that long. In a way that's OK with me, but if the new socket 939 mobo could run memory in single channel mode that might even be better, since 2x 512MB DDR400 RAM for dual channel operation would almost double the price I'd have to pay for only the mobo and an A64. And yes I know that single channel DDR266 isn't exactly top performing...

So, does anyone here know if single channel operation is possible with a dual channel A64? I know that (most if not all) P4 dual channel solutions are able to do that, but since the memory controller is on-die in A64s the situation could be entirely different.

By the way, considering that the memory controller is on-die, should I have posted this in the CPU forum instead? If so, please excuse me in advance...

 

[sisooktom]

I don't think 939 can run single channel. But at this point, you're going to pay a big premium for 939 chips and boards anyway. I'd go with 754, the money you save can cover a big chunk of your upgrade later. And 754 isn't dead or dying, they'll probably release a 3700+ for it, and after that it's going to be for the new Athlon XP line.

 

[mbf]

Thanks for your input. I don't really believe myself, that the 939 A64 can handle single channel memory. If nothing else, that would probably mean some sort of unwanted performance overhead.

Then again AFAIK all current A64/Opteron cores supposedly are the same and are binned according to their qualities. I believe someone wrote that 754 A64s often have one faulty memory channel and thus can be used as 754 single channel parts. Also speed binning is apparently going on since all A64s share the same thermal characteristics.

On the other hand, the 939 version is supposedly a completely revised core, so the above may not necessarily be true (any longer).

However, *if* it would be possible to run single channel on a dual channel 939 board, the 939 solution would be that more attractive. From what I can see socket 939 boards won't cost much more than socket 754 boards, and the price difference between the 3400+ (754) and the 3500+ (939) isn't *that* huge.

As for the 3700+ you mention, that was announced last week along with the two 939 chips, 3500+ and 3800+. The announced 3700+ is actually a 754 part.

As for the "new" AXP plans for socket 754, that I'm not too keen on. Seems to be a step back, if you ask me. Then again, noone knows exactly which capabilities the "new" AXP will have.

When all is said and done, I'll probably still go with a 754 rig. As you correctly point out, there's still a lot of money to be saved. But the 939 sounds awfully attractive... even more so if it could run single channel as well!

 

[glugglug]

Pretty sure that is WILL run single channel, and that is in fact what the AsRock 754/939 board does regardless of which DIMM sockets you fill.

Doesn't make sense to do this though, Socket 939 CPUs currently cost more than Opterons.

 

[mbf]

Interesting approach to this topic... I hadn't thought in that direction myself, but it makes very much sense when you think about it. Again, thank you very much for the input!