March4Revenge, this is a long post, but I suggest reading all of it as well as the links and also do some of your own research. If you are going to spend $4000-$5000 on a rig, you better know what you're buying.
As far as I know, the AMD Opterons (which I recommend since Xeons are limited to 800MHz bus shared) run bus at HTT (HyperTransport Technology) link speed at 800MHz and 1000MHz(1600MHz and 2000MHz effective from 2-way traffic). Single Xeon/P4 benchmark better in render than Opteron/AMD64 because Intel has HT (HyperThreading). The reverse is true in gaming because gaming demands higher memory bandwidth which AMD wins because of the integrated controller.
The specs change once we go to Dual-CPU setups (That's my route btw). I would say that the Workstation so far has been in a different time-zone until now...
Abit (surprisingly),
IWill, and
Tyan are now taking advantage of nVidia's nForce4 professional chips (which
LinuxHardware.org explains). The result is high-end workstation (3D rendering and the like) as well as high-end gaming (SLI configurations).
Dual Opteron vs Dual Xeon...
1) Xeon: Doing a quick search, most Xeons are on a 533 bus with the 800s just starting out. To be honest, I wouldn't settle for anything less than the 800bus right now (with EMT64). That immediately puts you at
$379 per CPU for the Intel Xeon 3.2EA GHz retail (based on the Nocona core & socket 604). Both the 533s and the 800s SHARE the same bus and the second Xeon has to get through the first Xeon to access memory. Sound inefficient?
2) Opteron: Most of the Opterons run at the 1600MHz HT bus (800 MHz both ways). This paired with the fact that the memory controller on the CPU, you have VERY fast memory access. AMD did their homework for scalability. When you add a second Opteron, the second one has it's own memory controller and it gets used as well... You have separated HT links for EACH cpu. This also allows for a technology called NUMA (Non-Uniform Memory Access) that allows each processor to access it's own memory at unheard of rates (I've seen over
10GB/s in benchmarks)! Also, Opterons start cheaper (you need the 2xx seriers in order for 2-way or 2-CPU setups).
You (March4Revenge) sound a lot like me. I want gaming, 3D rendering up the wazoo, and the best (nearly) I can get, and I want the best bang for the buck. I am also planning on spending about $3000-$4500 per system (I plan on 3 of these). Dual-CPU + SLI is getting me all giddy. I am personally looking at the
Abit WN-2S+ which boasts of features such as Dual-Opteron (1600MHz is listed for HT, but I'm sure that it will also support 2000MHz when the Opt252 becomes available), SLI in 8x/8x PCIE mode, 4-port SATAII (which may be just bearly enough... I would like to see 8, but I will only be using 4), and support for
un-buffered DDR400 ram! I expect this board to overclock as well. The dings... Only 8GB support (I only plan on using 4GB) and you HAVE to fill up all four slots. This board should be available in mid to late March. The IWill DK8EW looks to be a formitable foe (here's
a link to the SLI-gimped version since I don't have IWill's link for the EW). This board will support up to 16GB RAM, but has an onboard ATI RageXL VGA controller (ewwh, suppress it if you know what's good for you). This board will also support SLI (8x/8x) config. Both have only the nForce Pro 2200 chipset + AMD 8131 PCI-X Tunnel chip (which is why they are limited to 8x/8x in SLI mode). The
Tyan K8WE(s2895) is the best solution, also the most expensive (I like the Abit on as it will be <$300). It boasts 16GB max RAM, SLI in 16x/16x mode and has the most PCIE links (thanks to the setup: nForce Pro 2200 + nForce Pro 2050 + 8131 PCI-X Tunnel).
I'm personally leaning towards 2 Opteron 246s (Overclocks HT buss @ about 2020MHz or so) 4GB (4x1GB DDR400 low latency un-buffered RAM), 2-3 SATA 10K raptors AID0, 1 SATA media drive for storage, Abit WN-2S+, DVD, DVD+/-RW dual layer, 6800GT(s) eventually in SLI mode, watercooled... You will need close to a 660W PSU for all this. Pretty beefy rig.
As for you post about DDR2 concerns... Intel's bottleneck is the bus and the memory controller. DDR2 flaunts that bottleneck even more. Like I said before, NUMA on DDR400 (honestly man, you can overclock the memory to DDR500 easily with high quality Samsung TCCD DDR400 PC3200 RAM which at 200 the timings run at 2-2-2-5 timings) kicks Intel already on single CPU setups. Intels memory access does not increase with Dual-CPUs, but AMD does with NUMA.
*Special Note* Don't start buying components until mid-late march. That should be the end of Q1 when Intel and AMD release their latest and greatest and knock prices of existing down. Also, don't buy any of the mobos without reading reviews. I am waiting for the Abit reveiw and to see if un-buffered is really possible on a socket 940. Also, don't crap yourself out on RAM only going for capacity and now quality. I suggest anything with the Samsung TCCD chip for best overclocking. Also for the CPUs (Opteron) don't go for the 250s as they will have little overhead for overclocking the HT. The 246 has a lower multiplier and will give you more room to up the HyperTransport bus which gives you your faster memory access.
Hope this helps! I have done a LOT of research and would be happy to help! Cheers!
Arquero