Dual Core AMDs Not for Gamers...Why Not, *if You OCed Them?*

[aaronspink]

Originally Posted by jman1310

"The one limitation that both AMD and Intel have is bandwidth. In order to maintain compatibility with present day Socket-940 and Socket-939 motherboards, AMD could not increase the pincount of their dual core processors. The benefit is that AMD's dual core CPUs will work in almost all Socket-940 and Socket-939 motherboards (more on this later), but the downside is that the memory bus remains unchanged at 128-bits wide and supports a maximum memory speed of DDR400. So, while single core Athlon 64 and Opteron CPUs get a full 6.4GB/s of memory bandwidth, today's dual core CPUs are given the same memory bandwidth to share among two cores instead of one. " quoted from anandtech


seems like i was right, what's incorrect?

What part of the difference between "split evenly" and "shared between" don't you understand? You will be hard pressed to find any cases where there is signifiicant difference in performance between the dual core processors and the prior single core processors at the same frequency for single threaded workloads.

On top of that, there are few workloads outside of HPTC that are bandwidth limited.


Aaron Spink
speaking for myself inc.

[black_dante]

hmm. according to anandtech's article, i think that dual cores are worth it- if u are in the right demographic. If i had the cash, i'd rather buy the 4400 X2 with 1 MB than an fx 55. The game benches show that its about 90% of the performance but also 300 dollars less. you also get the benefits of multitasking/background programs and future proofing for multi threaded games. again, this is only if you have that kind of money (ie not for the masses). i think intel will win on that front, and amd fans will just have to wait till 06/07 for 65nm, the new socket/ddr2 and cheaper dual cores. i think that a heavily oc'ed venice for cheap will last me till then, which is fine by me.


just me 2 centavos

[jman1310]

Originally Posted by aaronspink

What part of the difference between "split evenly" and "shared between" don't you understand? You will be hard pressed to find any cases where there is signifiicant difference in performance between the dual core processors and the prior single core processors at the same frequency for single threaded workloads.

On top of that, there are few workloads outside of HPTC that are bandwidth limited.


Aaron Spink
speaking for myself inc.

the whole point of having dual cores is that you can multi-task with no performance hit. Joe stated earlier that he frequently games while encoding. On a dual cpu machine this is fine, however, because each has it's own memory. multi-tasking on a dual core will not yield similiar results, because each is using the same pipeline.

i was not talking about running a single thread - what's the point of spending the $$$ on a dual core then? but yes, if you are only doing one task, then there should be minimal difference

[aaronspink]

Originally Posted by jman1310

the whole point of having dual cores is that you can multi-task with no performance hit. Joe stated earlier that he frequently games while encoding. On a dual cpu machine this is fine, however, because each has it's own memory. multi-tasking on a dual core will not yield similiar results, because each is using the same pipeline.

What you think re-encoding a DVD takes bandwidth? Or folding? minimal impact. It will deliver performance with minimal difference except for extreme bandwidth cases of which there are few in the consumer space.

i was not talking about running a single thread - what's the point of spending the $$$ on a dual core then? but yes, if you are only doing one task, then there should be minimal difference

And that minimal difference is what you will see pretty much regardless. The vast majority of workload have minimal bandwidth requirements, esp with 1MB of L2 cache.

Aaron Spink
speaking for myself inc.

[Butcher]

Originally Posted by jman1310

the whole point of having dual cores is that you can multi-task with no performance hit. Joe stated earlier that he frequently games while encoding. On a dual cpu machine this is fine, however, because each has it's own memory. multi-tasking on a dual core will not yield similiar results, because each is using the same pipeline.

SMP boxes do not have their own memory per chip... They use the same memory and the same memory bus. This is why cache coherency and similar issues become such a problem. I don't see why a dual core is any worse than SMP, if anything it's better because it has the potential for a high bandwidth path between the CPUs as in AMD's solution.

[Ruiner]

I don't really see game devs bending over backwards to multithread anytime soon, unless Intel throws money at them to improve chip sales.
Most effort seems to go into *backwards* compatibility, not for bleeding edge stuff. A bigger install base improves game sales.
I was pleasantly surprised at how well Doom and HL downscaled to slower boxes. Take a look at the Steam hardware survey....there is a lot of old stuff there.
If multicore becomes mainstream priced by '07, expect *common* game support by '09. Sure, there will be a game or two tailored for it by next year, but probably just for showcasing the tech.

As far as OCing dual cores, I'm expecting mobo meltdowns similar to what was first seen when prescott was introduced. The procooling crowd won't have a problem cooling the cores of course. That won't be the limiting factor. I dont' see existing 939/940 board mosfets taking nicely to overvolting 2 cores.

[KuniD]

Originally Posted by Butcher

SMP boxes do not have their own memory per chip... They use the same memory and the same memory bus. This is why cache coherency and similar issues become such a problem. I don't see why a dual core is any worse than SMP, if anything it's better because it has the potential for a high bandwidth path between the CPUs as in AMD's solution.

Actually they do Its called NUMA, it stands for Non-Uniform Memory Access.

AMD's Opteron platform uses this. If you look at a dual (or quad) Opteron board you'll notice that each CPU has its own memory bank, so CPU1 doesn't have to go through CPU0 to access the memory. The memory banks and respective CPU's are connected together via hypertransport, which means a dual Opteron system has more than 11,000mb/sec memory bandwidth available.

On the new nForce4 Opteron boards (well the ones that use both the Pro2200 and 2050 chipsets), you effectively get two machines on one board. Each chip has its own chipset, memory bank, PCI-E 16x slot (with full 16 PCI-E lanes, not 8/8), and its own gigabit NIC. On top of that there's the AMD8131 PCI-X chip.

And on top of all of that its dual core ready Quite a few of reviews for dualcore chips have been tested on nForce4 Opteron platforms, ie the Tyan Thunder K8WE.

Whats even better is that these boards have nvidia nTune support for software OC'ing, but after lots of research a bunch of us have found out ways to OC the hell of out of the platform via BIOS and a few board mods

1.8ghz 244's running at almost 2.2ghz on stock voltage. As soon as we sort the voltage out, (and with the proper cooling of course) we'll be able to push these quite far.

Whether the dual-cores will clock as well is another story.

I plan on buying a pair or 244 E stepping Opterons until next year when I'll upgrade to dual core.

[aaronspink]

Originally Posted by Ruiner

I don't really see game devs bending over backwards to multithread anytime soon, unless Intel throws money at them to improve chip sales.
Most effort seems to go into *backwards* compatibility, not for bleeding edge stuff. A bigger install base improves game sales.
I was pleasantly surprised at how well Doom and HL downscaled to slower boxes. Take a look at the Steam hardware survey....there is a lot of old stuff there.
If multicore becomes mainstream priced by '07, expect *common* game support by '09. Sure, there will be a game or two tailored for it by next year, but probably just for showcasing the tech.

Your game engine doesn't support multi-processing? Well sorry about that 10+ million unit market you'll be missing.

Right now EVERY game engine is being reworked, along with every physics engine , AI, etc to support and perform well in a multi-processor enviroment. This is being driven not by the dual cores from Intel or AMD, but by the demand/requirements of the next generation console market.

Multi-core will be mainstream priced by this summer according to Intel's public roadmaps, with the vast majority of their processors sold being DC by the end of the year. In 2006 it will be hard to get a uni-core processor from either vendor.

[pHaestus]

Quake 3 supported SMP; does Doom3 engine not?

[Joe]

Q3's SMP was hardly functional from what I remember once you enabled that the game stopped working or slowed down.

[redleader]

Originally Posted by aaronspink

Your game engine doesn't support multi-processing? Well sorry about that 10+ million unit market you'll be missing.

Right now EVERY game engine is being reworked, along with every physics engine , AI, etc to support and perform well in a multi-processor enviroment. This is being driven not by the dual cores from Intel or AMD, but by the demand/requirements of the next generation console market.

Multi-core will be mainstream priced by this summer according to Intel's public roadmaps, with the vast majority of their processors sold being DC by the end of the year. In 2006 it will be hard to get a uni-core processor from either vendor.

You don't need to rework your engine to work on the new consoles. Theres nothing that says you have to use all cores. And if the cost is 3x as much for 50% better performance, the correct option may be to not use them.

[Joe]

YES They will be re-working console engines big time!

Read up on all the new console processors being "In Order" processors, not "Out of Order" processors like all the current ones.

Which means code wrote fro PC's and previous gen consoles will run slower than all hell on the new consoles due to the efficiency requirements for in order processors.

[DrCR]

Originally Posted by redleader

You don't need to rework your engine to work on the new consoles. Theres nothing that says you have to use all cores. And if the cost is 3x as much for 50% better performance, the correct option may be to not use them.

Duh, maybe I'm missing something here, but devs developting a game for the new xbox and ps really don't have a choice but to use the additional cores. If the game was hardware intensive at all and only support a unicore architecture bye bye frame rates. Imagine Splinter Cell: Chaos All Over Again at 5FPS...

:shrug:

[redleader]

Originally Posted by Joe

YES They will be re-working console engines big time!

Read up on all the new console processors being "In Order" processors, not "Out of Order" processors like all the current ones.

Which means code wrote fro PC's and previous gen consoles will run slower than all hell on the new consoles due to the efficiency requirements for in order processors.

Games aren't generally written in assembly, so you don't need to rewrite to deal with OOO verses not OOO. From the developer's perspective, this doesn't really make a difference.

Duh, maybe I'm missing something here, but devs developting a game for the new xbox and ps really don't have a choice but to use the additional cores. If the game was hardware intensive at all and only support a unicore architecture bye bye frame rates. Imagine Splinter Cell: Chaos All Over Again at 5FPS...

If anything, developers have shown that they'd rather get a game out on time then get a game looking well. You don't need to have amazing graphics to sell a console game. You do have to have a product before you can sell it. Rewriting a game engine to use more then one core is a tremendous undertaking that pushes up costs and development time, and given that games are generally not too limited by CPU, its one that I think many companies will not bother with. Instead they'll simply depend on the large increases in performance brought about by increased clock speed and GPU performance.

[aaronspink]

Originally Posted by redleader

You don't need to rework your engine to work on the new consoles. Theres nothing that says you have to use all cores. And if the cost is 3x as much for 50% better performance, the correct option may be to not use them.

They ARE reworking them. And the middleware they are using is also being reworked. All the physics engines are now fully multi-threaded for performance. It is happening.

Aaron Spink
speaking for myself inc.

[aaronspink]

Originally Posted by redleader

If anything, developers have shown that they'd rather get a game out on time then get a game looking well. You don't need to have amazing graphics to sell a console game. You do have to have a product before you can sell it. Rewriting a game engine to use more then one core is a tremendous undertaking that pushes up costs and development time, and given that games are generally not too limited by CPU, its one that I think many companies will not bother with. Instead they'll simply depend on the large increases in performance brought about by increased clock speed and GPU performance.

Actually you do need good graphics, and physics, and AI. And what idiot believes that games aren't limited by CPU? Lots of the newer games are limited by CPU. Physics is a big time issue in games at the moment.

Aaron Spink
speaking for myself inc.

[DrCR]

Yeah, I've been rather suprised by some of the posting in this thread. Maybe some of you are watercoolers, but not gamers or hardware geeks other regards....

[pHaestus]

If you're building a computer as a "gamer" then you'd get more bank for your buck by going up a step or two in video card than you will from this current iteration of dual core CPU. Especially on the AMD side because Intel plans to more or less give away the extra core on the desktops whilst AMD wants a premium for their chips. If you're talking about buying a CPU today to deal with next gen games then you're deluding yourself anyway. When they come out then mo' betta tech will as well.

[mastermind2004]

My "future-proof" plan is to go with an AMD 64 this summer, with a nice Socket 939 mobo, and SLI, and then upgrade to dual core when it is worth it.

[redleader]

Originally Posted by aaronspink

They ARE reworking them. And the middleware they are using is also being reworked. All the physics engines are now fully multi-threaded for performance. It is happening.

Aaron Spink
speaking for myself inc.

Who said anything about physics engines?

Actually you do need good graphics, and physics, and AI.

"good graphics, and physics, and AI" is a relative metric. You have to be good enough to sell, and you have to do it at an acceptable cost. Thats what counts. And you don't need parallel processing to get these things, as current games demonstrate, so I don't even see what you're trying to say.

And what idiot believes that games aren't limited by CPU? Lots of the newer games are limited by CPU.

What are you in the 3rd grade? Restating your opinion is not an argument. Neither is name calling.

What PS3 or Xbox2 games are limited by the CPU? How much does parallelization improve this? And at what cost?

[Butcher]

How many of you lot actually work in games out of interest?

Originally Posted by aaronspink

Your game engine doesn't support multi-processing? Well sorry about that 10+ million unit market you'll be missing.

Who cares? The PC market is tiny compared to consoles and has slimmer margins anyway. Further marginalizing your target isn't going to get you any more profit. PC game makers will only bother with SMP support once it becomes economical, which it isn't. Especially since you can run a single processor game on a SMP box.

Originally Posted by aaronspink

Right now EVERY game engine is being reworked, along with every physics engine , AI, etc to support and perform well in a multi-processor enviroment. This is being driven not by the dual cores from Intel or AMD, but by the demand/requirements of the next generation console market.

Your source on this? At least 50% of games are made cheap and quick and as long as it works and is reasonably on time and in budget they don't care. Reworking game engines is very expensive and not something people do lightly.

Originally Posted by aaronspink

Actually you do need good graphics, and physics, and AI. And what idiot believes that games aren't limited by CPU? Lots of the newer games are limited by CPU. Physics is a big time issue in games at the moment.

Almost all games are CPU limited, console or PC. However, around 90% of games don't run real physics so saying physics is the big thing is misleading. Besides which there's more milage doing physics on the GPU than doubling up your CPU cores, GPUs are getting faster a lot more rapidly than CPUs.

[maxSaleen]

For those who think multiple cores are inefficient for gaming I say:
Don't look at the PS3. It's a perfect coutnerexample. The PS3's CPU is a chip engineered and produced by IBM called the "Cell". Initially it will use 16 (not a typo) cores. I forget the frequency of each core but I want to say 1.2ghz. One core will be dedicated to distributing tasks and data among the other cores. This thing is going to suck memory bandwidth. It is using a special type of memory manufactured by RAMBUS (remember them?) known as XDR RAM. Initially this type of memory will offer 4.2gbs of bandwidth, supposedly with the ability to scale beyond 8gbs (I didn't believe it either, but its there on their site).

About heat:
I doubt it will be an issue. Just remember that the TIM will become more effective by having two cores under it. More surface area for heat dissipation. The winnie cores have been pretty cool running so far, though that 190w number is disconcerting. I doubt that AMD would introduce such a product line without the foresight to see a thermal issue (though Intel did it).

About gaming performance:
Your not going to see anything magical with dual core chips. Not intially, anyways. What you will have is the ability to run more programs at once. I would like to be able to run anti virus/spyware in the background, possibly rip a DVD/CD, maybe do some encoding, all without taking a performance hit. You've got to admit that would be handy.

About overclocking:
Thermals aside, dual core will inhibit overclocking. It is one thing to find one good chip for overclocking. It is another all together to find two, and then you'd have to have two good cores on the same chip... your chances are getting slim. Plus you have the issue of voltage regulation through your mobo.

Why dual core:
No where else to go, really. Think about this. It costs money to run debugging and all the QC that it takes to raise the speeds of a certain core architecture; at some point fab processes have to be changed which is very costly. Both Intel and AMD are seeing pretty high yields, plus they probably have overcapacity (remember that IBM fabs AMD's chips and Mac's chips). It would be cheaper for the companies to stick with their current fab process and slap two cores onto one chip and label it a performance boost than to re-engineer a chips architecture. In my opinion, thermal management becomes easier. Think about it. It would be easier to dissipate the heat from two 2ghz cores than it would be to dissipate the heat from one 4ghz core, assuming that they are all the same size.

[maxSaleen]

Remember that the PS3 is a multi billion dollar venture between IBM, Sony, RAMBUS, and their graphics provider (nVidia, right?). They wouldn't use a multi core processor if programming games for such a chip wasn't feasible. I just thought I would add that

[black_dante]

Remember that the PS3 is a multi billion dollar venture between IBM, Sony, RAMBUS, and their graphics provider (nVidia, right?). They wouldn't use a multi core processor if programming games for such a chip wasn't feasible. I just thought I would add that

xbox as well, it seems, is rumored to also have three(?) power pc cpus. programming games for smp is certainly possible, but b/c of its increased technical difficulty/complexity, it requires much more people (and thus money---> which especially hits pc devs).

For those who think multiple cores are inefficient for gaming I say:
Don't look at the PS3. It's a perfect coutnerexample. The PS3's CPU is a chip engineered and produced by IBM called the "Cell". Initially it will use 16 (not a typo) cores.

well, its not so much the cpus but the software that is not optimized. Server apps are smp optimized and thus scale nicely with more cpus. However, the tasks they do are more intrinsically smp-able than games/graphics engines are.

[aaronspink]

Originally Posted by Butcher

Who cares? The PC market is tiny compared to consoles and has slimmer margins anyway. Further marginalizing your target isn't going to get you any more profit. PC game makers will only bother with SMP support once it becomes economical, which it isn't. Especially since you can run a single processor game on a SMP box.

They aren't reworking them for the PC market. They are reworking them for the entirety of the market. ALL next gen platforms at multi-processor. ALL. Every one. The PC is merely along for the ride as far as games are concerned.

Your source on this? At least 50% of games are made cheap and quick and as long as it works and is reasonably on time and in budget they don't care. Reworking game engines is very expensive and not something people do lightly.

At least 100% of games are made off of game engines. The vast majority of these engines are either bought as a resource or designed internally but shared across many design teams.