SDRAM = SDR-SDRAM (Single Data Rate - Synchronous Dynamic Random Access Memory)
DDR= DDR-SDRAM (Double Data Rate - Synchronous Dynamic Random Access Memory)

DDR200 should perform better than any SDR memory (PC66/100/133/150). Don't know about RDRAM though.

But, seeing as you've listed three different chipsets, the real question should be, which chipset delivers the best memory performance.

Some of the P6 chipsets on paper:
533 MB/s (single channel PC66 SDRAM): Intel 440LX
800 MB/s (single channel PC100 SDRAM): Intel 440BX
1.06 GB/s (dual channel PC66 SDRAM): RCC ServerSet (Compaq Workstation 5100/6000)
1.06 GB/s (single channel PC133 SDRAM): Intel i815, VIA Apollo Pro 133A, ServerWorks ServerSet III LE
1.6 GB/s (dual channel PC100 SDRAM): ServerWorks ServerSet II LE (Compaq Workstation SP700, Intergraph TDZ 2000 GT1), Intel Profusion
1.6 GB/s (single channel PC800 RDRAM): Intel i820
2.1 GB/s (single channel PC266 DDR SDRAM): VIA Pro266T
2.1 GB/s (dual channel PC133 SDRAM): ServerWorks ServerSet III HE + 1 MADP, ServerSet III HEsl
3.2 GB/s (dual channel PC800 RDRAM): Intel i840
3.2 GB/s (quad channel PC100 SDRAM): SGI Cobalt (Visual Workstation 320/540)
4.1 GB/s (quad channel PC133 SDRAM): ServerWorks ServerSet III HE + 4 MADP

Real:
The RDRAM Avenger - Intel's i840 Chipset
DDR for Pentium III: 10 Boards with VIA Apollo Pro 266
ASUS Motherboard Round-Up
ServerWorks HEsl: DDR bandwidth without DDR SDRAM

i would put them in this order:
1. i840, the only decent rambus chipset for p3, but workstation oriented and very expensive and rare.
2. 440bx, best sdram performer but lacks official 133fsb, agp4x and udma100.
3. 815, best allrounder, slightly lower performance than bx but with official 133fsb support, agp4x and udma100.
4. via pro266(ddr), slightly faster than the 694.
5. via694, needs a lot of tweaking to work well but somewhat less buggy than previous via chipsets.
6. 820, poor actual performance and buggy.
7. via693, much slower and a lot more buggy than 694.

P6 is usually limited by the FSB. 64bit SDRAM matches up perfectly. In theory an excess of bandwidth at the northbridge might help other consumers like AGP. But I've never seen it proven to be tangibly beneficial.

Dual CPU setups have 2 FSBs so obviously can consume more bandwidth.

swaaye wrote:

Dual CPU setups have 2 FSBs so obviously can consume more bandwidth.

Almost all Intel CPU/chipsets before Nehalem (these have an integrated memory controller, so they NUMA instead of SMP) share the FSB in multiprocessor setups so the FSB transfer rate is limited to what the frequency provides (the exceptions are the Profusion, E8500, E8501 (2 busses, that's why their codename is Twin Castle), Intel 5x00 chipsets for the Core based Xeons (2 busses) and the Intel 7300 (4 busses)).

A dual P3 setup has a single FSB? I didn't know that.

I can't seem to find the benchmarks for it but basically it goes thus:

#1: Dual channel SD-RAM
#2: RDRAM
#3: DDR
#4: SDRAM

#1 is only found on the serverworks HE series chipset. which is dual p3 tualatins.
rd ram is faster than ddr, but has higher latency. honestly, its a tradeoff.

basically, the fastest chipset for socket 370 (pentium 3) is the serverworks HE-SL. If you don't want to use that, and are using 1ghz or slower chips, go 440. ddr and penium 3 never mixed well. and rdram is just stupid.

swaaye wrote:

A dual P3 setup has a single FSB? I didn't know that.

Its been that way for SMP back when people were just getting into micro computers and mainframes were still the envy but yes the a dual P5/6 system shared a single FSB. That was mainly due the L2 cache snoop and management of memory. 603/4 and 771 also shares the FSB between each socket cpu while modern SMP the memory controllers still have to be linked such as the case with 1567 aka Nehalem-EX.

I remember reading how they implemented something in K7 to make it less bandwidth limited with SMP, can't seem to find what exactly that was though...

Edit: Found it: http://www.zen26266.zen.co.uk/AMD-K7ii.htm

This EV6 bus will be especially useful for high end server and workstation machines as it implements "point to point" topology allowing CPU's to establish an independent link to the chipset. This of course is only of use in multi-processor systems but is a huge advantage over GTL+ in that each chip has its own connection to the chipset, whereas under GTL+ each processor must share one single connection. This allows up to 16 K7's to be run in a multi-processor system!

So the extra bandwidth of say i840 must be mainly for additional DMA IO performance.

For raw memory performance, anything at least as fast as the CPU bus speed is essentially the same.

The "best" one would be a ServerWorks HEsl quad-CPU rig. That would have two independent CPU buses with four total PC-133 memory channels (two per CPU bus.)

But for more mainstream use, including the fact that things like AGP cards and DMA devices (like hard drive and Ethernet controllers,) like to directly access system RAM, too, Apollo Pro 266 is probably fastest. It has both high-bandwidth *AND* low-latency. (Whereas dual RAMBUS on i840 may surpass it in raw bandwidth, it will be worse in latency.)

I haven't seen any reviews that actually prove that the single socket DDR or RDRAM chipsets help in a tangible manner. I even went digging for some AGP texturing tests on i820. And even if there were a big AGP texturing benefit, if any AGP texturing occurs heavily in a game it will cripple performance regardless of how fast AGP is working because AGP texturing is vastly slower than local VRAM on any reasonably fast card.

The funny thing is that this "ultra-fast" AGP texturing made an infamous return as "TurboCache" or "HyperMemory" on certain low-end PCI-E cards. What a pile of garbage that was, but a great way to advertise "512 MB!!!!!"...

So who owning i840 based computer and Pro266 Dual Socket (MSI Pro266TD-Master) motherboard?

Oh yeah, what about 440GX? Is it essentially same as 440BX?

440GX is a beefier version of the BX. Its designed for server applications, it drops support for edo dimms in favor of a 2gb memory limit. NX goes a step farther, and is designed for 4 cpus and 8gb of ram, but loses agp.

luckybob wrote:

440GX is a beefier version of the BX. Its designed for server applications, it drops support for edo dimms in favor of a 2gb memory limit. NX goes a step farther, and is designed for 4 cpus and 8gb of ram, but loses agp.

Bob, IIRC 440GX should also have two independant PCI buses

Also, doesn't 440nx only support EDO ram? This is a quite shady chipset (at least for me)

The Via Apollo Pro 266 would get my vote. I had a board based on that chipset (QDI Advance 12) and the performance was great. With a 1575MHz PIII-S and 1GB of CL2 DDR, that board produced an insane 12,400 in 3DMark01 with nothing but a stock-clocked 9800 Pro. Too bad the board itself was cheap junk that failed to POST most of the time (even when underclocked).

The 440bx and i815 offer roughly the same memory performance when bus speed is equal. The BX lets you install more RAM, but the i815 will let you crank the bus speed higher and has more robust AGP support.

The VIA 694/Apollo Pro 133 requires tuning. Out of the box, memory performance is lower than the BX and 815. But once you enable memory interleaving and tune the BIOS to perfection, it's just as fast as the Intel chipsets and supports far more memory. As for memory bandwidth, I get 852MB/s @ 151MHz FSB out of my TUV4X (cachechk7).

I've never used boards based on the i820 and i840. Most of the benchmarks I read back in the day placed the i820 behind the i815. The i840, on the other hand, was slightly faster.

subhuman@xgtx wrote:

Bob, IIRC 440GX should also have two independant PCI buses

Also, doesn't 440nx only support EDO ram? This is a quite shady chipset (at least for me)

The 440NX doesn't exist, as far as my knowledge goes. I guess you mean the 450NX that came out in 1998 for four-way 100Mhz systems and which did indeed support only FPM/EDO (up to 8GB) for some reason. No AGP support.

flupke11 wrote:

subhuman@xgtx wrote:

Bob, IIRC 440GX should also have two independant PCI buses

Also, doesn't 440nx only support EDO ram? This is a quite shady chipset (at least for me)

The 440NX doesn't exist, as far as my knowledge goes. I guess you mean the 450NX that came out in 1998 for four-way 100Mhz systems and which did indeed support only FPM/EDO (up to 8GB) for some reason. No AGP support.

Oh, that was a typo. I have never seen edo ram sticks designed to be used at 100mhz, besides the memory that voodoo2 cards have(which happens to be several times smaller than what is used n a home pc, even more in a server)