ddr333 vs 2x ddr266?

ddr400 vs 2x ddr266?

Basic Question: Given an nForce mobo with a fsb of 400Mhz and a total of 512Mb of system memory, would I get more performance with one stick of ddr400 or two sticks of ddr266 in dual-channel mode?

It seems to me that two sticks of 266Mhz memory would be much faster since the memory in that case would offer more bandwidth than the fsb.

If that is true (that 2x 266Mhz already outruns the 400Mhz fsb) then is there any reason to buy faster memory in the first place (ex 2xddr400 instead of 2xddr266)?

the only way you're going to get 400FSB using pc2100 (DDR 266) is to run your memory out of sync with the fsb. Not good. Especially not for an AMD rig. If you're using ddr400 and still running a 133FSB in sync then your memory bus is still only 266 DDR despite the use of DDR400 memory.

so really, the only way to answer your question is to say that no amount of memory dual channel or not will make a 133mhz fsb outperform a 200mhz fsb. (btw, for AMD there is no such thing as a 400mhz FSB, it's 200MHZ. Memory bus @ 200mhz fsb is 400mhz DDR.

The reason people buy ddr400 or faster ram is so that they can run 200mhz or faster fsb with memory in sync.

J.

Umm, no. a 400 mhz module will outperform 2 266mhz ones because it has more bandwidth. Plus running a 266 mhz module would mean that your CPU wouldn't be able to clock that high with the FSB at 1:1 ratio which is the strong point of AMD CPUs. In other words, get the DDR400.

With my mobo I can run a 400Mhz fsb (or 200Mhz if you would rather think of it that way) while running the memory at a slower speed. The reason I am asking this is that there was a similar issue on the Intel side... when the fsb started to outrun memory speeds people found they got more total bandwidth buy running the fsb faster than the memory (since there are other parts of the system that share the fsb bandwidth with the system memory). If I were running single channel ddr266 (133Mhz) on a ddr400 fsb (200Mhz) then my memory is the slowest part and the extra fsb speed would be useless, but it seems that using a dual channel system would mean that the ddr266 (133Mhz) memory would effectively run at ddr533 (266Mhz) and would provide more bandwidth than the ddr400 fsb (200Mhz). From my perspective two sticks of ddr266 (ddr533/266Mhz) would outperform one stick of ddr400/200Mhz as long as the fsb remains constant between the two scenarios.

I could be missing something so I could certainly be wrong here, but it's difficult for me to see how single channel ddr400 would outrun what would effrectively be ddr533 (yea, dual-channel ddr400 would outperform either setup, but I'm on a budget and can't afford that).

I think I have a friend with some ddr400 memory so maybe I can boorrow his stuff and test this situation out. Thanks for the input guys.

You could use dual DDR266, but I'de hate to see what your overclock would be if you're stuck with that speed ram. Just go with a higher speed ram (not nessasarily DDR400). It will pay of in the end when it comes time to overclock, and you could always reuse it should your processor be upgraded to something higher than 133 fsb, in which that slow memory might have some problems keeping up with your faster (fsb) processor.

But would 2x233 be better than 1x400? I don't think so. But the conclusion will have to wait for the tests.

No, one stick of DDR400 would be faster. Although it may seem that dual channel will double your memory bandwidth, in the nforce2 it only gives about a 5-10% bandwidth gain, far from the optimal 100%.