Oh wow... this has started to turn into a flame war...
RDram has on average higher latency than the SDram varieties. However, when the bandwidth is stressed, RDram will have *less* latency than any SDram variety. That is why RDram can easily reach its peak bandwidth much more easier than its SDram brothers. Thats why DDR400 SDram on an i845/Sis645DX platform BARELY manages to squeak by a PC800 system. Because of this, RDram will actually be better at high memory demanding applications (3d, compression, video encoding/decoding, blah blah) while it will comparatively suck at normal applications.
As for E7500 vs i860. You must think this out. E7500 is only operating at Dual channel DDR200 because of hardware limitations (Intel had problems with the clock multiplier to the frontside bus). You must also realized that e7500 is top of the line technology wise and that the i860 is almost 2 year old technology! Besides, RDram is hardly meant for serving. The more modules you add to it, the more latency that it will have (damn serial connections). RDram, IMO, shold only be used for high performance desktops/workstations.
Extremetech reviewed PC1066 RDRAM back in November of 2001. It compared it to DDR333 P4 setups, as well as AthlonXP machines. Their benchmarks showed PC1066's superiority for app's like Quake 3, but it also pointed out it's weaknesses and briefly discussed latency issues (I think, it's been a while since I read the review).
Yes thats is *very* true. However, that was November 2001, willamettes were barely pushing 2Ghz. Now that Northwoods are pushing over 3Ghz with an improved core, the performance gap of PC1066 and DDR SDram has intensified because of the CPU that is ABLE to demand the bandwidth offered by RDram. Before that time, the RDram bandwidth was more or less useless to the Pentium IV. With the advent of higher clock speeds, there comes the need for MORE memory bandwidth, especially on CPU intensive and memory intensive applications. With PC1066 RDram, the P4 enjoys a significant lead across the board against non-RDRam p4s, and that lead will only GROW as p4s become faster.
As for pricing, RDram is *cheaper* than DDR SDram. the best RDram (Samsung PC800) can be had for $70-80 for a 256 stick. Comparatively, a DDR266 CL2 from crucial is ... last time i checked, $90. Yes DDR SDram can be cheap, but those are either non-name brands OR BAD LATENCY (non CL2). With the cost of the motherboard included, the price is evened out.
Yes, DDR2 is still in development and I am fortunate to have gotten a sneak peek at what it can do. That's all I can and will say about it, and again I can't give you link to a review site, which are seemingly your only sources of information - how unfortunate for you.
Correct me if im wrong, but the only DDR2 chipset i have seen is a McKinley based server. Which btw, is a rather interesting piece of technology... but enough said about that. I dont work for AMD, so I cannot comment on the Opteron.
As for tomshardware and Tom pabst. You do realized that Tom Pabst was the #1 Rambus hater on cyberspace when the i820 and i840 chipsets for the Pentium III was out. Frankly, I find his reviews to be biased in his opinions, but his numbers usually dont lie. Even though he is biased, I do think he knows much mroe about computer hardware than Anand (tom can also be a bit pyscho too, imo).