OT: Building a new computer...

[Fyron]

Quad core desktop CPUs will be good in maybe 3-4 years. Stay far away from them for now if most of your time is not spent rendering hugely complex 3d models.

I thought dual or quad core meant 2 or 4 times the Mhz but I have gotten conflicting information that it is the speed listed but having 2 or 4 cores makes it process faster.

Not exactly. 2 cores is like having two discrete CPUs, so instructions from two processes can be executed at the same time. Each core is necessarily slower than a CPU that used the same process tech, but used the whole core. The reason why multiple CPUs/cores tend to be better than a big single one is that most processes (even games) don't really need all of instruction processing capacity of the last generation of single-core CPUs. Its better to split up the silicon so that the OS task scheduler has more leeway to manage applications (such as kernel and background processes). In theory, 4 cores are better than 2, since the system can process instructions from more processes concurrently.

When you compare a dual core to a quad core CPU, both made on the same silicon process level (45 nm now for the latest stuff, IIRC), a dual core tends to come out ahead in real world applications for home use. Each core has twice as much capacity to process instructions as a quad core CPU. On the other hand, a quad core CPU can process instructions from twice as many applications at once. There are pros and cons for each situation. When you have a ton of concurrent processes (or threads of one big one) running all the time, you want as many CPUs as possible. Servers tend to benefit greatly, as do workstations that do a ton of data crunching (or model rendering if the renderer is capable of using many CPUs). When you have just one app that is very CPU intensive, its better to have a dual core CPU.

Games don't really lend themselves to many concurrent threads. There is a lot of optimization that can be done with 2 threads, but going to 3 or 4 is usually redundant, since the extra tasks that could be split off tend to be far less process-intensive than the main threads. Plus, multi-threading in games is still nascent; most devs are still trying to wrap their heads around two concurrent threads, much less many.

In summation, ignore quad-core CPUs for the next few years. Dual-core CPUs should net performance gains with modern games (and are more than sufficient to run older games). Quad-core CPUs should net performance losses with almost all existing games, and most games under development.

[Randallw]

Thanks, I'll remember to stick with dual core then and leave the quad stuff for the one after that then. Either that or keep an eye out to see if the games I'm after use quad stuff, though I see by your explanation that probably won't be.

About the only other thing I have running when I game is music. That and I don't bother closing internet windows. I have a couple of coasters though that taught me to close everything else when I burn DVDs.

I actually went into a new store and said I was after a top end system. The salesman, maybe after a big commision, pointed out to me a big quad core system. I said to him

"ok I said I wanted top end but I didn't mean that much"

he then pointed out the systems along the back wall.

[Raapys]

To my knowledge there's no real cons against quad core( except price, and bigger cooling and power requirements ) compared to dual core. Intel's quad core CPUs, the only quad cores available at the time, are simply two of their dual cores put together on one chip. Given the same clock frequency, a quad core and a dual core will perform equally in applications/games that only support one or two cores.

The catch here is, as mentioned, the price. The 3ghz dual core costs the same as the 2.4ghz quad core.

Personally I think it's only about a year or so before most( if not all) new games released will take some advantage of quad core, though.

[Fyron]

High power consumption (leading to much greater total cost of ownership and noisier cooling systems), poor cost/frequency ratio, and little benefit to various existing game engines (including UE3) make quad core not as attractive at this juncture. Sure you'll get a few more frames per second from some crappy FPS titles, but its not (IMO) worth the cost.

I think its going to be (much) more than a year before quad core starts to make sense for gaming. Its good for applications with more load-balanceable parallelization, of course.

[Raapys]

Well, as mentioned in that Q&A you linked to, the UE3 does gain some small benefit from more than 2 cores. Crysis, another major title released within a few weeks, is supposed to benefit greatly from more than 2 cores. Valve's next version of the Source Engine is also being developed to benefit greatly from more than 2 cores.

These are all games/engines of this year, and many other games will be using these engines as a base. That's why I think that already next year we'll see most games supporting, to some degree, more than 2 cores.

Already there's a few games like Supreme Commander that takes very good advantage of quad core.
Interestingly, the 2.4ghz quad core actually outperformed a *4ghz* dual core in the game Lost Planet(Link). That's some good developing.

Again note that I do not actually support buying a quad core before the next generation of them appears within the next few months, though. Then we'll probably see much better cooling, power consumption, etc.

[Fyron]

More flash in the pan FPS games that will differ little from the simpler flash in the pan FPS games of yesteryear, beyond more shininess... yay...

Supreme Commander seems to make some relevant usage of multi-threading though, what with the need for actually intensive AI processing in a RTS as compared to the few "living" things present at a time in a FPS and all.

[Raapys]

True, graphics and FPS seems to be where most of these increased number of cores are wasted. If SEV had good support for multithreading I'd consider getting a 4core even if only for that game, though; it'd make turn processing far less of an annoyance. Probably very hard to add if the game wasn't made with multithreading in mind, though.

[Will]

Raapys said:
To my knowledge there's no real cons against quad core( except price, and bigger cooling and power requirements ) compared to dual core. Intel's quad core CPUs, the only quad cores available at the time, are simply two of their dual cores put together on one chip. Given the same clock frequency, a quad core and a dual core will perform equally in applications/games that only support one or two cores.

The catch here is, as mentioned, the price. The 3ghz dual core costs the same as the 2.4ghz quad core.

Personally I think it's only about a year or so before most( if not all) new games released will take some advantage of quad core, though.

The other con is the amount of die space available for on-chip cache. Normally about 50-67% of the space on a modern microprocessor is taken up by cache; if you take a dual core and squeeze another two processing units onto the chip, you are either going to: A) cut out some parts of the processing cores, B) reduce the amount of total cache, or C) take a lot more power. The only way to get around this is to reduce your process size (e.g. 65nm to 45nm), but then you can use the same process on dual cores, and you end up with the same trade-off.

For intel chips, the most apples-to-apples dual v. quad comparison I could find is the E6850 (dual) v. QX6850 (quad). Both have the same FSB @ 1333MHz, both have 32kiB L1 and 2MiB L2 per core, and both operate overall at 3.0GHz. The difference is power: the E6850 takes 65W @ 0.962V-1.350V; the QX6850 takes 135W @ 1.100V-1.372V. That means you'll need a lot more cooling for the quad core. On benchmarks, doing raytracing (by nature a multi-threaded process) or other image manipulation in 2d or 3d gives around 10-25% advantage to quad core. Compilers, web servers, etc. actually do better with dual cores, compression gives <10% advantage to dual core except with h.264 which seems to give a nearly 50% advantage to quad core. And then games... the differences are so small as to be negligible.

And then comes the cost: QX6850 will cost you around $1000. E6580 about $250. And power consumption is 69W v. 17W while idle, and 136W v. 67W under load. Which means that the E6850 will cost less to run under full load 24/7 than the QX6850 if it is idle 24/7. At my electricity prices (~$0.11 / kWh), that amounts to $66.50/year to run the quad core 24/7, vs. $16.50/year to run the dual core.