Forget DDR3, fastest DRAM is XDR
4.8GHz octal data rate blows minds
THINK THAT INTEL'S X48 chipset will be fast, with 2GHz DDR3 memory to accompany it? Think again - Intel's old pal Rambus has them beaten like a grouse in hunting season.
Elpida has just announced that it has the industry's fastest DRAM, with its new XDR part running at a meltingly fast 4.8GHz. XDR is the Rambus standard for next-gen platforms, and its memory is included in the PS3, along with that console's bonkers Cell processor.
The Elpida RAM comes in 512MB chips, and runs at a 9.6GB/s transfer rate, which is about six times standard DDR2-800. You can also forget your average double data rate - this stuff runs with an octal data rate of 600MHz to get to 4.8GHz. Crazy.
Its manufacturers are touting it around as a good solution for a new wave of HDTVs, servers and workstations. Don't expect to see it showing up in your gaming rig anytime soon, however - production won't start until April 2008, and we can't see Intel being too keen to take another stab at a Rambus platform. µ
Comments
DDR2-800 has 6.4GB/s bandwidth...
... per channel, which means that common dual channel motherboards have 12.8GB/s theoretical bandwidth with DDR2-800 PC2-6400 RAM modules.So, how comes 9.6GB/s is six times 6.4GB/s ?
Also, future Intel Nehalem high end motherboards are supposed to have quad-channel DDR3 and DDR3-1600 PC3-12800 modules have a theoretical bandwidth of 12.8GB/s per channel. So on a dual channel motherboard that's 25.6GB/s and on a quad-channel it would be 51.2GB/s ....
sigh...
...with tons of new hardware and less and less software to utilize it, for a common PC user, I doubt people will be thrilled with the bandwidth... It's nice for server environment and some professionals, but the rest of the folk... Not to mention all new boards and stuff even for DDR3...Dull as a horses' b...
PS3 has XDR..
Doesn't the PS3 have 256Mb of XDR and 256Mb of DDR3?Bandwidth != performance
..at least not always. One of the big problems with RDRAM wasn't bandwidth, it was latency. Married with a chip with a long pipeline you had a combination which could kill performance when the input data/instruction streams aren't suitably arranged and/or during context switches.XDR should be much better architecturally from the latency point of view, and we seem to have stop chasing ever higher CPU clocks - all good news - but real world performance, including latency issues, should be looked at before we slather too much over the new memory bandwidth king.
Faster, in this context, is very often not the same as quicker.
Just me 2p worth
XDR and spursengine
we can't see Intel being too keen to take another stab at a Rambus platform.??What about this?
http://gizmodo.com/photogallery/qosmiospursengine
May be Intel has to face challange. Sony, IBM and Toshiba createt the Cell Chip (using XDR) for a lot of money, now they put it into their own products. Not so bad.
Latencies & XDR2
Well the latencies found on the XDR are very very low.See wikipedia to find more.
The version 2 of XDR (XDR2) has been announced some months or even I believe like a year ago.
If someone read chinese could try to translate this article.
http://www.stor-age.com/zhuanti/htm2005/05080800ZC5D.asp
DDR2-800 doesn't have 6.4GB/s...
... bandwidth, a DDR2-800 DIMM has that bandwidth. The DDR2-800 DIMM is 64-bits wide so that equals 0.1GB/s per bit. 4.8 GHz XDR listed in the article is for 16-bit wide chip which gives 0.6GB/s per a bit which is six(6) times DDR2-800. The article is not very clear on this. Times these GB/s per bit rates with the bit width of the module to get the bandwidth of the module. So for a 64-bit + 64-bit (dual channel) you would get 76.8 GB/s for 4.8GHz XDR.c'mon
Lets not be citing wikipedia, nowDDR2-800 has 6.4GB/s bandwidth...
This post is true but I think it is meant that 9.6*8 = 76.8GB/s and 76.8/12.8 is 6...so it is 6 times.XDR2 8.0GHz 16GB/s
XDR2 DRAM devices are targeting 8.0GHz data rates, enabling a single DRAM device with 16GB/s of peak bandwidth. Micro-threading increases the usable bandwidth by reducing column-access granularity to 16 bytes per device. The result is a traditional 8-bank CMOS DRAM core with the performance of a 16-bank memory device. XDR2 memory interfaces will also use Rambus's proven FlexPhase™ timing circuitry with additional adaptive timing features for a more robust signaling environment at high bandwidth. The XDR2 architecture provides the capability to scale data rates beyond 8.0GHz and will provide chip and system designers with the features they need to achieve the highest performance using the fewest number of controller pins and DRAM devices.Pricing?
So is it going to cost as much as I think it will? Like, it's made from parts of endangered snow leopards, and priced as such?If it's a component of the PS3, was it another reason that thing might require refinancing one's home to purchase?
XDR on Intel is easy, but AMD needs a new silicon
Intel CPUs aren't tied to any memory types since the memory controller is on the northbridge chipset. Just as Intel made chipsets for FBDIMMs, DDR2 and DDR3, it isn't for them hard to migrate to XDR. Other chipset manufacturers can do the same. IBM has the X4 chipset for Tigerton that uses DDR2 instead of FBDIMMs for example. Until XDR becomes more popular, DDR3 will be the next thing on PCs..Meanwhile AMD on the other hand is tied down by its own design - the memory controller is on the CPU itself. Moving to a new memory type isn't as easy.
Criminal
It really seems criminal that XDR is not in use in systems today, it’s not even on the freakin roadmaps either!I understand it takes a hell of a lot of work to introduce a new memory format into a chipset but to not even have nVidia or ATi use it in some truly awesome high end cards is just ridiculous, did they sign a 10 year contract with DDR or something?!!
DDR3 is octal data rate
I'm pretty sure that DDR was double data rate, DDR2 was actually quad and DDR3 was octal. At least, the number of DRAM words transmitted per clock has doubled each time. So in what sense is XDR's "octal" data rate different from DDR3's?Escuela
Yet another reason teachers need to drop using the word 'times' in math class and stick to 'multiplied by'.Sheesh.