The only reason why RDRAM is faster is because the FSB is "quad-pumped". Normal FSB is at 100mhz. If something like NVIDIA's twin-bank architecture ever shows up for the P4 platform (where it can be fully utilized), then there is no doubt that DDR will be faster. And DDR also has lower latency compared to RDRAM.
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DDR vs RAMBUS (Still Unsure)
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> pm, *who* told you RDRAM runs hot? have you ever touched it?
At PC800 speed, RDRAM runs cooler than DDR. It only gets hot when you overclock approaching PC1200 speeds, as you would expect in overclocking from 400MHz to 600MHz (or 100MHz to 150MHz). Of course, all Samsung RDRAM ships with a heat spreader.
> I really could careless about benchmarks I'm only after real-world performance
> (who could care about anything else?) and so far I havent found compelling evidence to
> show rambus beating out DDR 2100,
RDRAM destroys PC2100, PC2700, and even DDR400 in bandwidth-intensive games like Serious Sam. As you can see right here at GamePC, a 2.1GHz P4 with PC1066 RDRAM outperforms a 2.1GHz P4 with 176MHz DDR by nearly 40% in the Serious Sam "crusher-type" benchmark. Right here, Aceshardware found the old/obsolete Williamette P4 2.0GHz, paired with PC1160 RDRAM, to outperform the "Northwood" P4 2.0GHz with PC2100 DDR by 18% in a different Serious Sam test; the same old Williamette P4 2.0GHz with RDRAM also outperformed the Northwood 2.0GHz with PC2700 DDR by 9%; it even outperformed a Northwood 2.2GHz with PC2100 DDR by 5%.
And Aceshardware was only able to hit PC1160 speed because they equipped four lesser-quality Corsair RIMMs. Current Samsung RIMMs (on Samsung PCB) can approach or hit PC1200 speed in the 128Mb size, or PC1160-PC1200 speed in the 256Mb size. Some on Hardforum.com have even hit PC1250 speeds with stock PC800 Samsung RDRAM. With the "official" PC1066 RDRAM that ships in late April and May, PC1200 RDRAM (through slight overclock) should be the norm, with some running PC1250 to PC1300 speeds. In May, many here will likely purchase the 2.26GHz P4 with 533FSB for $220 online after the price drop, and run it at 17x162.5=2762MHz with PC1066 RDRAM overclocked to PC1300 speed.
At PC800 speed, RDRAM runs cooler than DDR. It only gets hot when you overclock approaching PC1200 speeds, as you would expect in overclocking from 400MHz to 600MHz (or 100MHz to 150MHz). Of course, all Samsung RDRAM ships with a heat spreader.
> I really could careless about benchmarks I'm only after real-world performance
> (who could care about anything else?) and so far I havent found compelling evidence to
> show rambus beating out DDR 2100,
RDRAM destroys PC2100, PC2700, and even DDR400 in bandwidth-intensive games like Serious Sam. As you can see right here at GamePC, a 2.1GHz P4 with PC1066 RDRAM outperforms a 2.1GHz P4 with 176MHz DDR by nearly 40% in the Serious Sam "crusher-type" benchmark. Right here, Aceshardware found the old/obsolete Williamette P4 2.0GHz, paired with PC1160 RDRAM, to outperform the "Northwood" P4 2.0GHz with PC2100 DDR by 18% in a different Serious Sam test; the same old Williamette P4 2.0GHz with RDRAM also outperformed the Northwood 2.0GHz with PC2700 DDR by 9%; it even outperformed a Northwood 2.2GHz with PC2100 DDR by 5%.
And Aceshardware was only able to hit PC1160 speed because they equipped four lesser-quality Corsair RIMMs. Current Samsung RIMMs (on Samsung PCB) can approach or hit PC1200 speed in the 128Mb size, or PC1160-PC1200 speed in the 256Mb size. Some on Hardforum.com have even hit PC1250 speeds with stock PC800 Samsung RDRAM. With the "official" PC1066 RDRAM that ships in late April and May, PC1200 RDRAM (through slight overclock) should be the norm, with some running PC1250 to PC1300 speeds. In May, many here will likely purchase the 2.26GHz P4 with 533FSB for $220 online after the price drop, and run it at 17x162.5=2762MHz with PC1066 RDRAM overclocked to PC1300 speed.
Athlon4all
Diamond Member
Great stuff KenAF. Totally agree!
> Buisness apps DDR performs better due to lower latency
The higher you clock RDRAM, the lower the latency. PC1066 RDRAM has comparable latency to PC2100 DDR, and PC1200 RDRAM has significantly lower latency than PC2100 DDR.
With identical clock speed, these tests show that PC1066 RDRAM improves performance in running through MS Office application tests by 10% over PC800 RDRAM, and PC1200 RDRAM improves performance (over PC800) in the same tests by over 17%. Unlocked P4 processors were used for the test.
The P4 definitely seems to benefit from the 30-40% improved latency that PC1066 RDRAM has over PC800; the 33% improved bandwidth doesn't hurt either. Clearly, the P4 @ >2.0GHz is capable of higher IPC than we are seeing now; it needs the bandwidth and latency of PC1066-PC1200 RDRAM to achieve its full potential.
The higher you clock RDRAM, the lower the latency. PC1066 RDRAM has comparable latency to PC2100 DDR, and PC1200 RDRAM has significantly lower latency than PC2100 DDR.
With identical clock speed, these tests show that PC1066 RDRAM improves performance in running through MS Office application tests by 10% over PC800 RDRAM, and PC1200 RDRAM improves performance (over PC800) in the same tests by over 17%. Unlocked P4 processors were used for the test.
The P4 definitely seems to benefit from the 30-40% improved latency that PC1066 RDRAM has over PC800; the 33% improved bandwidth doesn't hurt either. Clearly, the P4 @ >2.0GHz is capable of higher IPC than we are seeing now; it needs the bandwidth and latency of PC1066-PC1200 RDRAM to achieve its full potential.
Amused
Elite Member
<< I didnt know that intel was only phasing it out of there servers... But that is usually a sign of going the way of the dodo... generally things come down to the desktops from the servers and workstations... what incentive does intel have to keep rambus around when the price and longevity of DDR is virtually limitless... I'm not saying DDR is netter but I'm saying I dont see how intel could keep making rambus chipsets as a good business move (unless they have too because of there contract..) >>
Intel made the plan to phase out RDRAM in servers when RDRAM cost 2-3 times as much. Servers need mega-RAM, and Intel did not want to alienate custumers by requiring RDRAM in applications that require such huge amounts of RAM. It's an outdated, but committed business plan that will probably reverse itself here pretty quickly.
Your right, my how things change in a couple of months since I last looked at . . .
From Tom's
RDRAM is the only type of memory that can make use of the increased bandwidth of the fastest CPUs. Still, RDRAM has had to fight against a big problem from the start in order to make it in the mass market: the price for the module is higher than that of SDRAM. Much has been made of the price vs. performance ratio of RDRAM, but the truth is that RDRAM is expensive to produce and cannot be produced or tested on the current equipment that most DRAM companies currently have.
From a current standpoint, DDR is sure to be the memory of choice in the next 12 months - after DDR333, fast memory with DDR400 and DDR533 is planned. From Intel itself, there's only support for DDR266 for now, but ultimately Rambus, based on PC1066 specifications, should create a breath of fresh air.
In recent years, Intel may have made more technological progress than the market could handle in such a short period of time. Maybe that progress was the ultimate problem.
We ultimately believe that in hitching its processor roadmap to Rambus, Intel is ensuring its ability to push CPUs into higher speeds. Rambus has a clear cut roadmap that Intel can target, and that's been the case since the beginning.
So I guess if your going P4 RDRAM all the way, no question. . . Today anyway 😉
From Tom's
RDRAM is the only type of memory that can make use of the increased bandwidth of the fastest CPUs. Still, RDRAM has had to fight against a big problem from the start in order to make it in the mass market: the price for the module is higher than that of SDRAM. Much has been made of the price vs. performance ratio of RDRAM, but the truth is that RDRAM is expensive to produce and cannot be produced or tested on the current equipment that most DRAM companies currently have.
From a current standpoint, DDR is sure to be the memory of choice in the next 12 months - after DDR333, fast memory with DDR400 and DDR533 is planned. From Intel itself, there's only support for DDR266 for now, but ultimately Rambus, based on PC1066 specifications, should create a breath of fresh air.
In recent years, Intel may have made more technological progress than the market could handle in such a short period of time. Maybe that progress was the ultimate problem.
We ultimately believe that in hitching its processor roadmap to Rambus, Intel is ensuring its ability to push CPUs into higher speeds. Rambus has a clear cut roadmap that Intel can target, and that's been the case since the beginning.
So I guess if your going P4 RDRAM all the way, no question. . . Today anyway 😉
xxsk8er101xx
Senior member
well if you remember Intel is dropping RDRAM. DDR is intels choice and thats that.
SO if you go rdram your next upgrade you will have to ditch your ram and go with ddr. However, by then DDR II or whatever idea they have for newer "DDR" RAM will be, you'll have to buy a new stick anyway.
It's a gamble so. But with a 2ghz pentium 4! i don't think you'll need to upgrade for awhile .
I would go rdram.
SO if you go rdram your next upgrade you will have to ditch your ram and go with ddr. However, by then DDR II or whatever idea they have for newer "DDR" RAM will be, you'll have to buy a new stick anyway.
It's a gamble so. But with a 2ghz pentium 4! i don't think you'll need to upgrade for awhile .
I would go rdram.
<< pm, *who* told you RDRAM runs hot? have you ever touched it? I have.. it's roughly the same temperature as my BaracudaATAIV... >>
I work as an engineer for Intel and I have a lot of experience with RDRAM. I set up a little over one hundred IBM Intellistation MPro workstations that use 4GB of RDRAM each and I have babysat a couple of them when they've had trouble. And I have worked on several testbed systems. The older RDRAM RIMM heat spreaders get untouchably hot. Well over 45C. The newer ones are much better - they use a smaller process technology and they don't leave as many banks open. There's a smaller performance hit over the old method but there's a substantial difference in temperature. I made my comment about heat because the ratio of the older hotter RIMMs vs. the new cooler RIMMs that I have personally worked with is well over 100:1 (yes, 100:1, all of the IBM boxes have the older ones (that's 8 RIMMs each) and then a half dozen testbeds, and I have seen maybe 8 of the newer ones).
KenAF, I based my comment about performance on personal experience and reviews like these here at Anandtech (Sis645 chipset review) and at Tom's Hardware (i845DDR review). Aside from the synthetic memory bandwidth benchmarks, in neither article is there any substantial performance difference between 266DDR (Sis645 and i845) and 333DDR (Sis645) and PC800 RDRAM (i850). The difference never exceeds 10% and most of the time is under 3%.
I will admit that I have, and I have had for quite a while, a bias against RDRAM. I have a predisposition to dislike the memory because I don't particularly like the memory interface or the company behind it (and not for the obvious reasons, either). I would never even consider buying an RDRAM based system for my home computer. But in all things I try to look at things objectively and it seems to me that an Sis645 board with DDR266 or DDR333 is very nearly as fast as an i850 with RDRAM. The difference seems to be neglible. Perhaps my predisposition is coloring my views slightly, but the Aces article is not an apples to apples comparison, and Serious Sam is not the only application that I would use to judge performance. In other apps, and in other articles, the various chipsets (and their corresponding memory) seem to be more evenly matched.
Wow.. be careful what you wish for, as you just may get it. ;p
That's a lot of great info and appreciate everyone adding to this thread.
This system I'm building is home based, will be used for work, but is primarily a gaming rig.
Seems to me that if performance is the main objective, and I have no plans to over-clock, then Rambus is the way to go. That said, PM makes some very good points and I share some of his personal concerns/preferences.
I think I have all the information I need and now its just a matter of making up my mind. One thing appears clear; either way I go will yield results I can live with for quite some time.
Thank you,
Terrapin
That's a lot of great info and appreciate everyone adding to this thread.
This system I'm building is home based, will be used for work, but is primarily a gaming rig.
Seems to me that if performance is the main objective, and I have no plans to over-clock, then Rambus is the way to go. That said, PM makes some very good points and I share some of his personal concerns/preferences.
I think I have all the information I need and now its just a matter of making up my mind. One thing appears clear; either way I go will yield results I can live with for quite some time.
Thank you,
Terrapin
pm,
The difference is you are talking PC800 RDRAM. PC800 RDRAM offers no benefit over a system with PC2700 DDR. PC1066 RDRAM does, and PC1200 offers a substantial benefit over PC2700 DDR. Current PC800 RDRAM RIMMs from Samsung have no trouble at PC1066 speed, and many can hit or approach PC1200 speed. Of course, you need the right motherboard and processor too.
If you are just going to buy a RDRAM system and run it at stock PC800 speed...then you might as well go with a PC2700 DDR, cause it will get you equal or better performance, and you'll be able to reuse the memory when dual channel DDR motherboards ship at the end of the year. If, however, you are going to buy a PC800 system and run it at PC1066 or better speed, then RDRAM is definitely the way to go. Likewise, if you can wait until May when PC1066 becomes the new "stock memory speed," also go for RDRAM.
The difference is you are talking PC800 RDRAM. PC800 RDRAM offers no benefit over a system with PC2700 DDR. PC1066 RDRAM does, and PC1200 offers a substantial benefit over PC2700 DDR. Current PC800 RDRAM RIMMs from Samsung have no trouble at PC1066 speed, and many can hit or approach PC1200 speed. Of course, you need the right motherboard and processor too.
If you are just going to buy a RDRAM system and run it at stock PC800 speed...then you might as well go with a PC2700 DDR, cause it will get you equal or better performance, and you'll be able to reuse the memory when dual channel DDR motherboards ship at the end of the year. If, however, you are going to buy a PC800 system and run it at PC1066 or better speed, then RDRAM is definitely the way to go. Likewise, if you can wait until May when PC1066 becomes the new "stock memory speed," also go for RDRAM.
<< either way I go will yield results I can live with for quite some time >>
Exactly. There's just not a large enough difference. It seems the closer two products are to the same performance class, the more threads pop up to argue one or the other, the more zealots pickup pitchforks and start poking, and the more insane the tone of the boards.
xxsk8er101xx
Senior member
pm,
Interesting point of view. I like it.
I would only go with RDRAM do to price. 😉 .. I actualy should have said "whatever is cheaper". Since it's pretty much a gamble. Usually you want to go with a memory brand that you'll use in your next upgrade. In my opinion. And Since DDR is the choice for both AMD and Intel. *shrugs* ... it's a gamble you can go both ways.
Thats why i say (or should have said) go with whatever is cheaper.
Interesting point of view. I like it.
I would only go with RDRAM do to price. 😉 .. I actualy should have said "whatever is cheaper". Since it's pretty much a gamble. Usually you want to go with a memory brand that you'll use in your next upgrade. In my opinion. And Since DDR is the choice for both AMD and Intel. *shrugs* ... it's a gamble you can go both ways.
Thats why i say (or should have said) go with whatever is cheaper.
Well, PM, my bad. I see you have quite the quallification. If that's true though... then why do my samsung DIMMs say no touch when they're only warm? Is that because they never bothered to change the heatspreader markings? It's rather funny..
Old RAMBUS=As hot as my Barracuda ATAII (Untouchably hot in an uncirculated air enviornment, right now i'm using a PII heatsink to cool it..., runs around 45C without heatsink in uncirculated enviornment)
new RAMBUS=As hot as my Barracuda ATAIV (30C, bearable..)
Old RAMBUS=As hot as my Barracuda ATAII (Untouchably hot in an uncirculated air enviornment, right now i'm using a PII heatsink to cool it..., runs around 45C without heatsink in uncirculated enviornment)
new RAMBUS=As hot as my Barracuda ATAIV (30C, bearable..)
<<
<< Surprised nobody mentioned that Intel is phasing out RDRAM over time.
Not that it matters for the current decision, but one less reason to choose Rambus. >>
Myths die hard, don't they? Intel is only shelving RDRAM for servers. One media outlet got a hold of the story, and made it seem like they were phasing out RDRAM for all applications. That's just not true. Intel's roadmap has RDRAM in it for some time to come. >>
Wrong, Intel's roadmap shows no new platform (aka chipsets) supporting RDRAM. There are a couple revised chipsets in the next 12 months that continue to support RDRAM. You don't have to believe me, but look at Intel's just-released mobile P4 CPU + chipset. It's DDR only, and as many Intel watchers may know, the mobile platform often reflects where the desktop will be in 6-12 months.
Basically, Intel chose RDRAM because of the performance potential. However, they became completely turned off by the fraudulent actions of Rambus. Furthermore, the bottom line is that the industry has not adopted RDRAM and scaled up production as much as Intel had planned on. Even if RDRAM is technically superior (which is still a difficult argument to prove), it's a moot point if DDR is mass produced by the fabs in greater quantity.
But like I said, the fact that Intel is now ditching RDRAM over time doesn't really impact the current P4 purchasing decision.
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