P4 and DDR

[Guest]

I heard from my friends that there are now P4 with DDR mobos now. Is it true? So how does it perform compared with P4 and RDRAM? I read alot of Raystonn's articles and I'm pretty convinced that RDRAM will perform better under heavy workloads.

Plus another curious question. So if th P4 (northwood) can be scaled up from 2GHZ to 10GHZ in the future using the same pins, I assume, and more software will become recompiled plus SSE2 optimized, and the IPC of the P4 increased with the new Northwood, the P4 will become faster than anything AMD or Cyrix would have to compare. Is this assumption a good one or bad?

But there's something that concerns me. There's a blue heatsink covering the whole piece of RDRAM. Either that means this type of RAM heats up really fast or it's pure cosmetics.

We put text in here and that's our signature?

 

[Guest]

"I heard from my friends that there are now P4 with DDR mobos now. Is it true? So how does it perform compared with P4 and RDRAM? I read alot of Raystonn's articles and I'm pretty convinced that RDRAM will perform better under heavy workloads.

Plus another curious question. So if th P4 (northwood) can be scaled up from 2GHZ to 10GHZ in the future using the same pins, I assume, and more software will become recompiled plus SSE2 optimized, and the IPC of the P4 increased with the new Northwood, the P4 will become faster than anything AMD or Cyrix would have to compare. Is this assumption a good one or bad?

But there's something that concerns me. There's a blue heatsink covering the whole piece of RDRAM. Either that means this type of RAM heats up really fast or it's pure cosmetics.

We put text in here and that's our signature?"

 

[girish]

hi
as far as i know, there is no P4 DDR motherboard right now. the Brookdale chipset with DDR support is due Q4 or Q12k2.
and there is no other chipset vendor making P4 chipsets as yet, although I heard that intel has licenced ALi and SiS to make them. no VIA i suppose!

well, with dual channel rdram that gives a 400 MHz "effective" fsb and a whopping 3.2gig bandwidth, it is possible it would perform better under heavy load conditions. but a question remains, what kind of load we are talking about?

northwood will be coming with more pins, 478 against 423 as P4s have right now. basically that only means Northwood will need larger current, and most of these 55 extra pins will supply more current to the core. maybe a few will be used for multiprocessor signalling and other tasks. it might be scales higher than 2GHz (not 10, as a thread is on discussing that) but it wont be due to its hyperpipeline or low IPC, it would be due to sheer fabrication technology (it would be made on 0.13 micron process against 0.18 micron current) and better organisation.
and performance or software compatibility is not dependent on number of pins, just that newer P4s will need newer motherboards, software will still work.

as far as AMD and Cyrix are concerned, Cyrix is far behind making budget/value processors. I guess by the time Northwood arrives AMD will be already having Palomino Athlons at 2+ GHz. thats what their roadmaps say. and as far as performance goes, it still takes a P4 1.7 GHz to compete against 1.33 GHz Thunderbird. that says a lot.
and word is around that Palomino (i may be wrong with Athlon, but the Hammers will surely) will support SSE2! that will be the day!

as for RDRAM, its both yes and no. basically this heatsink is supposed to distribute the heat evenly over all the chips, and offer a nice housing to the RIMM as well. i guess this heatsink is necessary for even heat distribution to maintain same temperatures (and thus properties) of the chips on the RIMM.

girish

<font color=blue>die-hard fans don't have heat-sinks!</font color=blue>

 

[Raystonn]

"I heard from my friends that there are now P4 with DDR mobos now"

DDR chipsets for the Pentium 4 will not be available until Q1 of 2002.

"RDRAM will perform better under heavy workloads"

It will. SDRAM (DDR and SDR) suffers from the dead wait cycles when switching from reading to writing and back. This happens all the time in normal applications and multitasking OSes. This penalty will not show up in synthetic benchmarks that do separate batches of reading and writing in different tests.

"Is this assumption a good one or bad?"

I would say it's good speculation. But remember that it's just that. Speculation can easily turn into religious wars.

"a blue heatsink covering the whole piece of RDRAM"

This is to distribute heat evenly along the whole memory module. All types of memory eventually heat up under heavy load. RDRAM is the first (I'm sure DDR SDRAM will add this eventually) to protect against heat damage in this way.

-Raystonn

= The views stated herein are my personal views, and not necessarily the views of my employer. =

 

[Raystonn]

"what kind of load we are talking about"

Pretty much any common load. Current synthetic benchmarks don't test where SDRAM (DDR or SDR) has its biggest issue. This is when switching between reading and writing and vice versa. It incurs dead wait cycles that RDRAM does not. In standard applications, intermittent reads and writes are happening all the time. The more applications you have running, the more this affects your system. The only type of application where SDRAM shows low latency is in the synthetic benchmarks that do a bunch of reading without writes, or a bunch of writing without reads. These are unrealistic conditions for normal applications.

"Northwood will need larger current"

Usually when a CPU moves to a smaller die, the power requirements drop. The Pentium 4 is no different in that respect.

"wont be due to its hyperpipeline"

Actually this is what allows the high ramp up in clock speed. The increases pipeline spreads out components and stages that had previously been lumped together. With the P3, a few of these components/stages had reached maximum clock speeds and because of this, held back the rest of the pipeline as a bottleneck. Spreading out the pipeline allows the components/stages to be isolated and the clock speeds to be ramped up without hitting any bottlenecks.

-Raystonn

= The views stated herein are my personal views, and not necessarily the views of my employer. =

 

[ksoth]

The problem I have with comparing RDRAM to DDR SDRAM in terms of performance is there are no equal system tests to perform such comparisons. The main thing right now is DDR SDRAM Athlons system perform better than RDRAM Pentium 4 systems in most real world test, not synthetic benchmarks. The only way we will truly know which is a better memory type is when the Brookdale Pentium 4 DDR chipset comes to market. That way you have the same processor that can be used with both memory types, which is the perfect way of determining which type is better. However, we saw that PC133 SDRAM usually performed better than RDRAM on Pentium III systems, but it isn't quite a fair test because Pentium IIIs maximum bandwith could not utilize RDRAM to its bandwith potential. Brookdale, or a possible RDRAM Athlon chipset (?), is the ultimate test in determining which memory type is truly better.

"We put the <i>fun</i> back into fundamentalist dogma!"

 

[peteb]

Actually I think the P4 is beginning to edge out from the current 1.33 Athlons on some real world applications at a 1.7G speed. The Northwood _should_ really emphasise this unless Intel screw something up or AMD don't get their new chips out.

I think Brookdale (from what I've seen) will be a barge and perform no better (or poss. worse) that a good PIII setup.

-* This Space For Rent *-
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[peteb]

"So if th P4 (northwood) can be scaled up from 2GHZ to 10GHZ in the future using the same pins"

I don't think anyone has said anything about a 10Ghz P4 having the same socket or pinout - just that the core will get there. The socket has already changed after 3 cpu releases (1.3, 1.5, 1.7) so I see very little hope that Intel will now keep the new socket configuration of the next three years. Maybe they will though - 370 is pretty stable.

-* This Space For Rent *-
email for application details

 

[Ncogneto]

Ray you say you work for intel. Now let me see.....intel told us how great that Rdram was going to be and how it would boost performance for the p3 before the I810-I840 (whee they dismal failures or what?) series of motherboards was produced. So then it gets released and guess what? No increase in performance, Intel lied to us. Surely you can go on and on about the fact that it took a processor specially designed to use the bandwith of Rdram( which is a$$backwards to begin with) and now that we have the p4 we can truely see how superior Rdram is. But the fact still remains, Intel told us that Rdram was going to help the p3 and it didn't. So, now, why should we believe you ( an Intel employee) when you say that a p4 with ddr will not peform up to the levels that it would with rdram. Are you forgetting that DDR can also have a dual channel memory controllers as well?

As for the fact of DDR ram ever having heatsinks, seems rather unlikely as DDR ram draws less power and dissapates less heat that SDRAM let alone Rdram.

A little bit of knowledge is a dangerous thing!

 

[Raystonn]

"DDR ram draws less power and dissapates less heat that SDRAM let alone Rdram"

Do you have any numbers to back this up? By the way, DDR is SDRAM. The only different is it transmits twice per clock instead of once. The actual design is the same.

As far as RDRAM versus DDR, RDRAM has built in throttling capabilities to move RAM into a sleep state when it's not being used. This is much the same as is done for CPUs in notebooks. It has merely been expanded to work with RAM as well. This makes for less power consumption when power management features are enabled.

-Raystonn

= The views stated herein are my personal views, and not necessarily the views of my employer. =

 

[Kelledin]

DDR is the same design as SDRAM, but it runs on a lower voltage (2.5 vs 3.3). Assuming the memory still draws the same amperage, power consumption is lower.

Anyone have details of DDR vs. SDRAM amperage?

And what about SO-DIMMs (standardized laptop memory)?

Kelledin

bash-2.04$ kill -9 1
init: Just what do you think you're doing, Dave?

 

[Ncogneto]

you would think that someone that works for intel would be aware of that.

A little bit of knowledge is a dangerous thing!

 

[Ncogneto]

Do you have any numbers to back this up? By the way, DDR is SDRAM. The only different is it transmits twice per clock instead of once. The actual design is the same.

<font color=red>Although the technical realization may be a lot more difficult, the basic principle of DDR-SDRAM is very simple. While the new memory module is clocked at the same speed as normal SDRAM, it is able to transport double the amount of data by using the rising as well as falling edge of the clock signal for data transfers. We are all aware of this technology since AGP2x and JEDEC is already working on the DDR II spec, which will double the data transfer once more, using the quad-pumped technology known from AGP4x or the upcoming Pentium 4 bus. DDR-SDRAM has another important improvement over PC133 SDRAM. Its voltage supply is using only 2.5 V, instead of 3.3 V. This and the lower capacities inside the memory chips lead to a significantly reduced power consumption, which makes DDR-SDRAM also very attractive for notebooks. </font color=red> takem from THG
<A HREF="http://www6.tomshardware.com/mainboard/00q4/001030/athlon-02.html" target="_new">http://www6.tomshardware.com/mainboard/00q4/001030/athlon-02.html</A>

A little bit of knowledge is a dangerous thing!

 

[Raystonn]

Touchy today are we? Let's test your knowledge. Can you tell me the voltage requirements for PC800 RDRAM? I'll save you the trouble. RDRAM runs at 2.5 volts. There is no difference in wattage or heat between RDRAM and DDR SDRAM.

-Raystonn

= The views stated herein are my personal views, and not necessarily the views of my employer. =

 

[Raystonn]

Yes, that's all basic knowledge. I asked you to back up this statement you made: "DDR ram draws less power and dissapates less heat that SDRAM let alone Rdram." That statement infers that DDR SDRAM draws less power and dissapates less heat than RDRAM. RDRAM has the same voltage requirements, 2.5 volts, as DDR SDRAM. So far nothing you have said has backed up your statement.

-Raystonn

= The views stated herein are my personal views, and not necessarily the views of my employer. =

 

[Guest]

> Plus another curious question. So if th P4 (northwood)
> can be scaled up from 2GHZ to 10GHZ in the future using
> the same pins, I assume, and more software will become
> recompiled plus SSE2 optimized, and the IPC of the P4
> increased with the new Northwood, the P4 will become
> faster than anything AMD or Cyrix would have to compare.
> Is this assumption a good one or bad?

I would say the assumption is poor, because you assume that only Intel is moving forward. I'm certain that by the time "in the future" (as you say) when P4 reaches 10 GHz, AMD processors will be there as well.

Leo

 

[Guest]

Wattage = Volts*Amps. To see how they compare we also need to know what the current/amps they are drawing.

100W and 40w bulb both are 120v, but draw different current....

ThermalTake has a DDR memory cooling sinks out, but other than looks it seems like they serve no real purpose. Think HardOCp has a link to a reveiw...

<font color=blue>The #1 reason to upgrade your PC - to run faster benchmarks...</font color=blue>

 

[Guest]

I dont believe you are working for intel. If you were working for intel you would know that rambus ram is using alot more power than sdram.
Thats one of the resons why it was never used in notebooks.

 

[Raystonn]

"rambus ram is using alot more power than sdram."

That sure is a common misnomer. It is however completely untrue. Operating at 2.5 V, the Direct RDRAMs will operate in four modes: active, standby, nap and idle. If four 128-Mbit devices are on the Rambus channel, one device could be active, consuming 300 milliwatts of power, while three others could be in nap mode, consuming 11 mW each. Overall, RDRAM will be less power hungry than the SDRAMs.

"Thats one of the resons why it was never used in notebooks."

You will see Pentium 4 notebooks using RDRAM very soon.


-Raystonn

= The views stated herein are my personal views, and not necessarily the views of my employer. =

 

[Ncogneto]

One of the biggest strengths of RDRAM is its clock-speed, but this has also been a source of many of its problems. Running at these higher speeds, both RIMMs and motherboards must be manufactured with much more stringent tolerances and with shorter trace lengths to avoid signal corruption from electromagnetic interference (EMI). This adds a double-whammy to the system price. Additionally these factors complicate designing RDRAM systems as demonstrated by Intel with its i820 fiasco.
High speeds create an even greater problem: heat. A single tiny RDRAM chip can consume several Watts of power making the device very, very hot very, very quickly. In fact, the chip could quickly burn up if this heat is not siphoned away. Due to this, RIMMs are most often manufactured wrapped in a metal heat sink. It is also recommended that a fan blow directly across RIMMs to help dissipate this excess heat.
<A HREF="http://www6.tomshardware.com/mainboard/00q1/000315/rambus-03.html]" target="_new">http://www6.tomshardware.com/mainboard/00q1/000315/rambus-03.html]</A>

Heat IS an Issue
Despite the new arguments to the contrary, heat IS an issue. RDRAM and its controlling chipsets have elaborate thermal regulating circuitry to insure that no device overheats. According to Paul DeMone <http://www.realworldtech.com/page.cfm?ArticleID=RWT112299000000&PageNum=4>, a respected expert on memory technologies, when pages are open on an RDAM device, the single tiny RDRAM chip can consume nearly 4W! Obviously the little chip could burn up quickly if not properly cooled.
Unlike SDRAM, this heat can be concentrated into a single chip. As a remedy RDRAM has a special heat sink so that the heat from one chip can be pulled away and dissipated across the heat sink as well as the other chips it comes in contact with (as with most heat sinks, each chip has a thermal interface to insure efficient heat transfer, so in actuality the heat sink does not truly touch the RDRAM - that would be ineffective).
If there wasn't a problem with heat, then RIMM's would not come with the pricey heat sink attached to them. This heat sink is also called a heat spreader, but understand that the later is a subset of the former, despite strange arguments to the contrary <http://www.anandtech.com/showdoc.html?i=1239&p=8>.
A Hot Tradeoff: Performance vs. Energy Consumption
Open pages can be viewed as tiny caches on RAM devices. RDRAM is capable of having more open pages than SDRAM, which should help it latency wise, but in actuality a page read in RDRAM has a hit comparable to bank read latency on SDRAM. Additionally, as stated above, an active RDRAM device consumes a lot of power and gets hot quickly.
So there is a tradeoff: more open pages, higher energy consumption, more heat (and possibly less stability), but better performance, versus fewer open pages, less energy consumption and less heat, but also poorer performance. The current RDRAM systems are performing a careful balancing act, and the heat sink is the balancing pole that allows RDRAM to run a little faster across this tightrope to improve performance.
//www6.tomshardware.com/mainboard/0...little bit of knowledge is a dangerous thing!

 

[ksoth]

The heat and power issue between DDR SDRAM and RDRAM I think is a very minor one. I mean, Athlons produce far more heat and consume more power that Pentium IIIs and I think even Pentium 4 (not sure though). The main issue we need to be concerned with is performance, and the strengths and/or weaknesses of the two types has yet to be seen on a similar platform. Once that happens, then we'll truly know which is best. Although, you'd think that an RDRAM solution would perform atleasr *as good* as an SDRAM solution for Pentium III, but that was not the case, although I think the dual-channel RDRAM solution performed pretty close. If RDRAM is truly so great, why did it perform sub-par to a supposed inferior memory type?

"We put the <i>fun</i> back into fundamentalist dogma!"

 

[Raystonn]

"High speeds create an even greater problem: heat"

DDR SDRAM has the same problems as RDRAM in this regard. Higher speeds will always cause more power consumption, and therefore more heat. DDR SDRAM is not immune from this.

"Unlike SDRAM, this heat can be concentrated into a single chip"

This is actually the key reason why many people think RDRAM produces more heat than SDRAM. Over the whole memory module, the average heat dissipation is going to be about the same as that of a DDR SDRAM module running at approximately the same speed. The heat spreader keeps heat from building up in small areas of the memory module. Over the whole module however, (i.e. on average), the disappated heat will still be about the same as DDR SDRAM once it reaches the levels of performance of RDRAM.

The main differences between DDR SDRAM and RDRAM once bandwidth equalizes between the two will be latency during normal system use (reads and writes intermingled) and the unique power management features of RDRAM, especially useful in conserving power in notebooks during less demanding applications.

-Raystonn

= The views stated herein are my personal views, and not necessarily the views of my employer. =

 

[Ncogneto]

No, your missing the point, while what you say makes perfect sense in terms of desktop systems, heat and power consumption are very much an issue in the laptop segment. This is why we do not have Athlon powered notebooks. This will be addressed with the release of the mobile palimino.

A little bit of knowledge is a dangerous thing!

 

[Raystonn]

"If RDRAM is truly so great, why did it perform sub-par to a supposed inferior memory type?"

For an answer to that question we must look to the benchmarking software that was used in the comparisons. SDRAM (SDR and DDR) has a well known problem switching from reading to writing and vice versa. This incurs great latency penalties. Were the benchmarks working in a way that avoided this problem altogether? Did they do a batch of reading separate from a batch of writing? This is usually the case with synthetic memory benchmark applications, and hence you get results that do not mimic real-world performance.

-Raystonn

= The views stated herein are my personal views, and not necessarily the views of my employer. =

 

[ksoth]

By my statement I was refering to the desktop market. But even for mobile applications, the differences between the two are probably so small that they would hardly make a difference in terms of having too much heat or battery length. Considering the RAM of a system consumes a very small portion of the overall power of the battery (display, video, CPU all consume the vast majority), it's something, that altough beneficial, is not crucial. Sure, DDR SDRAM consumes less power than SDR SDRAM, but all systems currently out there are running just fine on SDR SDRAM. I mean, how much battery life would DDR SDRAM actually save? A few minutes in terms of a several hour battery life?

"We put the <i>fun</i> back into fundamentalist dogma!"