What happened to the SIS Quad Channel RDRAM P4HT chipset?

[Akumajou]

What happened to the SIS Quad Channel RDRAM P4HT chipset?

Basically the SIS R658 was announced back in 2003 but saw no release as it was replaced with the R659 in 2004 and the R659TX for Q1 2005 the latter being able to provide the Intel Pentium 4 with Hyper Threading the following support:

800Mhz FSB (possible 1066FSB support)
Four 16bit channels
PC 1600 RDRAM support
PCI-Express X-16 support (no AGP support)

With Intel Prescotts being slightly bested in some benchmarks by competing AMD 64 processors don't you think that having a RDRAM mobo with quad channel support would give the Prescotts a shot in the arm lead?

Unfortunately AMD 64 cpus cannot use RDRAM so even though some still hate the memory company you cannot deny the performance lead it game Intel back in the days so please don't turn this into an Intel vs AMD topic since this is only for Intel cpus.

Then there is the possible arrival of official support from Intel of Rambus Inc.'s XDR-DRAM (get it XD-RDRAM) providing even more bandwith increases once either the dual core Pentiums are released or the P4HTs with 2MB of L2 cache.

Also with the knowledge of the Pentium M with its 2MB L2 cache being a performance demon wouldn't it make sense for SIS to also make a quad channel RDRAM P-M chipset?

 

[T2k]

I highly doubt it will ever make it to the market... it'll be extremely expensive , and Intels are already losers in price/performance...

 

[hovz]

"slightly bested"

 

[Guden Oden]

As it "requires" 32-bit RIMMs (which are two 16-bit RIMMs sandwiched together) to be practical I'm sure it'll never see the light of day. These RIMMs are extremely rare and undoubtedly equally expensive. I doubt people would accept buying their memory off ebay just for the privilege of quad memory channels...

 

[arjan de lumens]

Re: What happened to the SIS Quad Channel RDRAM P4HT chipset

With Intel Prescotts being slightly bested in some benchmarks by competing AMD 64 processors don't you think that having a RDRAM mobo with quad channel support would give the Prescotts a shot in the arm lead?

Unfortunately AMD 64 cpus cannot use RDRAM so even though some still hate the memory company you cannot deny the performance lead it game Intel back in the days so please don't turn this into an Intel vs AMD topic since this is only for Intel cpus.

I just don't think it will help all that much:

• Supplying more bandwidth than what the processor's FSB is capable of handling traditionally doesn't help performance very much.
• RDRAM still has an inherent latency disadvantage compared to DDR1, which may not be big, but probably still large enough to cancel out the benefits of the extra bandwidth.

A Pentium-M chipset with quad-channel RDRAM makes even less sense; much of the good performance of the Pentium-M is due to the large L2 cache and the way it keeps down the need for off-chip memory traffic; so you will end up throwing lots and lots of bandwidth at a processor that just plain doesn't need it and can't make use of it.

 

[Guden Oden]

Just saying RDRAM has higher latency than DDR is a bit imprecise. RDRAM allows many more memory pages to be open. With 4 independent memory channels, that's a massive amount of simultaneously open pages.

 

[T2k]

Re: What happened to the SIS Quad Channel RDRAM P4HT chipset

A Pentium-M chipset with quad-channel RDRAM makes even less sense; much of the good performance of the Pentium-M is due to the large L2 cache and the way it keeps down the need for off-chip memory traffic; so you will end up throwing lots and lots of bandwidth at a processor that just plain doesn't need it and can't make use of it.

YEah, that's a common disinformation, urban legend here about P-M chips.

 

[Akumajou]

Re: What happened to the SIS Quad Channel RDRAM P4HT chipset

I just don't think it will help all that much:

• Supplying more bandwidth than what the processor's FSB is capable of handling traditionally doesn't help performance very much.
• RDRAM still has an inherent latency disadvantage compared to DDR1, which may not be big, but probably still large enough to cancel out the benefits of the extra bandwidth.

A Pentium-M chipset with quad-channel RDRAM makes even less sense; much of the good performance of the Pentium-M is due to the large L2 cache and the way it keeps down the need for off-chip memory traffic; so you will end up throwing lots and lots of bandwidth at a processor that just plain doesn't need it and can't make use of it.

But most of that performance increase that P4s got with DDR was because of PAT technology, prior to that when P4s had RDRAM/DDR/ and SDRAMs versus AMD and DDR, P4 cpus had an overwhelming performance lead (2002) so basically I just don't think that what you said jives with 2 years ago when no Intel PAT was around.

I'm sure that SIS is no Intel when it comes to making a chipset but already P4HTs have 800Mhz FSB and 1066Mhz on the EE and next year we are probably looking at either a mature .09nm process or the new .065nm process to either increase L2 cache to 2MB or probably increase clock speeds.

As it "requires" 32-bit RIMMs (which are two 16-bit RIMMs sandwiched together) to be practical I'm sure it'll never see the light of day. These RIMMs are extremely rare and undoubtedly equally expensive. I doubt people would accept buying their memory off ebay just for the privilege of quad memory channels...

I highly doubt it will ever make it to the market... it'll be extremely expensive , and Intels are already losers in price/performance...

Well AMD 64s are not the affordable CPUs of 2 years ago with their current near Intel prices and I would not mind if SIS would make an RDRAM chipset compatible with older AMD AthlonXPs (non 64) so that the AMD crowd has an option to buy the memory but that will likely never happen.

Still, when I made this topic of RDRAM I was not thinking about it being affordable, I just thought about extreme performance where price is not an object or a limit just like the few out there buying P4HT EEs, P4HT 3.8Ghz with liquid cooling systems, DDRII, the hard to find ATI high end cards, Nvidia 6800 Ultras for SLI (btw I think current SLI is just a waste of money but it moves technology forward)

 

[Fox5]

What huge performance advantage of RDRAM?
http://techreport.com/reviews/2001q1/p4-vs-athlon/index4.x
Here it looks more like the athlon with ddr has a slight overall advantage over the p4 with rdram, and it's much cheaper. Now if we're talking about northwood maybe things would be different, but dual channel northwood systems outperform rambus systems as well as athlons. Well, i865 + northwood + 533fsb + dual channel went back and forth with the athlons, though intel usually had a faster processor out sooner, the 3200+ xp beats the 3.06ghz p4, and then the p4c's came out and blew away both the athlon xps and the p4b's.

 

[Akumajou]

What huge performance advantage of RDRAM?
http://techreport.com/reviews/2001q1/p4-vs-athlon/index4.x
Here it looks more like the athlon with ddr has a slight overall advantage over the p4 with rdram, and it's much cheaper. Now if we're talking about northwood maybe things would be different, but dual channel northwood systems outperform rambus systems as well as athlons. Well, i865 + northwood + 533fsb + dual channel went back and forth with the athlons, though intel usually had a faster processor out sooner, the 3200+ xp beats the 3.06ghz p4, and then the p4c's came out and blew away both the athlon xps and the p4b's.

So... are you saying that you agree that SIS should make their Quad Channel RDRAM chipset for current Socket 478 and LGA 775 Intel Pentium 4 Processors with Hyper Threading?

And yeah that bench was done with the first P4 cores at 1.5Ghz 400Mhz FSB, current cores have SSE3, HyperThreading, 800 and 1066Mhz FSBs and much higher clock speeds.

 

[Fox5]

What huge performance advantage of RDRAM?
http://techreport.com/reviews/2001q1/p4-vs-athlon/index4.x
Here it looks more like the athlon with ddr has a slight overall advantage over the p4 with rdram, and it's much cheaper. Now if we're talking about northwood maybe things would be different, but dual channel northwood systems outperform rambus systems as well as athlons. Well, i865 + northwood + 533fsb + dual channel went back and forth with the athlons, though intel usually had a faster processor out sooner, the 3200+ xp beats the 3.06ghz p4, and then the p4c's came out and blew away both the athlon xps and the p4b's.

So... are you saying that you agree that SIS should make their Quad Channel RDRAM chipset for current Socket 478 and LGA 775 Intel Pentium 4 Processors with Hyper Threading?

And yeah that bench was done with the first P4 cores at 1.5Ghz 400Mhz FSB, current cores have SSE3, HyperThreading, 800 and 1066Mhz FSBs and much higher clock speeds.

So wouldn't it seem that all those other features are what gave the p4s the advantage and not RDRAM? Why not make a quad channel ddr board?

 

[Akumajou]

So wouldn't it seem that all those other features are what gave the p4s the advantage and not RDRAM? Why not make a quad channel ddr board?

Well ...cause DDRII is there and... thats... pretty much more... DDR.

 

[Fox5]

So wouldn't it seem that all those other features are what gave the p4s the advantage and not RDRAM? Why not make a quad channel ddr board?

Well ...cause DDRII is there and... thats... pretty much more... DDR.

Well, quad channel ddr2 then?
If there is some kind of benefit to be had from going quad channel, can't it be done with ddr/ddr2 the same as rdram?
Ok, I'll assume rambus can give more bandwidth than ddr, but at the expense of latency. What would that help with? Video/photo editing and 3d rendering?