Questions on how Dual Core operate (for future gaming rig)

[Mulattothrasher]

(Sorry if this has been asked before)

Can you have 2 gig on one processor and say, 1 gig on the second one and everything work without problems? Do they ever work in tandem if only one game or application is running? For example, say I am playing MTW2, would I only have 2 gig running it, while the 1 gig on the other core is waiting for another application to open so it can run the second application, or, will the extra 1 gig start working with the 2gig stick and thus run the application with 3 total gigs?

My Athalon XP 2600 1.5 RAM 256 Nvidia 5700LE Video card is fine for now with all games that I play, MTW2 being the most demanding (everything is overclocked as far as I could push it, and had it for about 4 years with no problems. I cannot help but overclock everything, sorry). Seems the dual processors are the up and coming big thing now, not the mention quad cores. I hope to upgrade in the near future and need some guidance from those in the know. Thanks in advance...

[Niccolo Machiavelli]

What do you mean by gig? CPU clock frequency? They're typically equal in both cores.

And considering gaming: It depends if the game has dual-core support...

[General Sun]

Not as far as I know, you cannot simply distribute processing power to whatever application you choose. The application needs to be written to take advantage of the dual core ability. However, you will find dual core to be very useful when you multitask. Dual or Quad core is clearly the way to go, I'm not sure if I answered your question or not...

[Aristocrat]

Multi core cpus at the moment have the same frequency on both cores. In the future this may change, but not yet.

If a game is written to take advantage of multiple cores then different tasks are allocated to the different cores. One may, for example work on physics while the other works on AI. (Which is a generalisation, so please don't jump on me people).

For games that aren't written to support multiple cores (older games from last year and before, and some games this year) then you actually see a performance decrease, as the cores typically run at a lower clock frequency then older cpus, overclocking the cpus, which is laughably easy for almost every multi-core cpu out there, solves this little issue.

For some games you have to use the windows task manager to assign one of the cores to run the game, the other cpu will run windows background tasks.
*In KoTOR II for example, using a dual core cpu means the game is unstable, and movement doesn't work. Doing the above however, and the game works fine. (bugs aside).

[Erik]

For games that aren't written to support multiple cores (older games from last year and before, and some games this year) then you actually see a performance decrease, as the cores typically run at a lower clock frequency then older cpus, overclocking the cpus, which is laughably easy for almost every multi-core cpu out there, solves this little issue.

Actually, clock frequency has nothing to do with the performance loss.
A Core2Duo core on 2 GHz will run any game faster than a P4 core on 2.5GHz.

The performance loss is due to extra overhead.
You see, rather than running on a single core (as you might expect), those games will switch cores every few milliseconds and this means everything in the L1 cache needs to be copied from one side of the chip to the other side, a few hundred times per second, and that takes some time.

Overclocking won't remove this overhead.
But assigning a single core (like you have to do with KoTOR II) to the program will.

The performance loss is only 1% or so, and since it only applies to older games (which usually run like lightning on modern CPU's anyways) it's not really something you need to worry about.

[Simetrical]

The performance loss is due to extra overhead.
You see, rather than running on a single core (as you might expect), those games will switch cores every few milliseconds and this means everything in the L1 cache needs to be copied from one side of the chip to the other side, a few hundred times per second, and that takes some time.

If it's just a few hundred times per second, the effect should be unnoticeable. Latency of L1 cache transfers can't be on the order of more than a couple of nanoseconds, which repeated a few hundred times a second amounts to maybe 500 nanoseconds of lost time tops. A program using only 1 ms of CPU time per second would still see a loss of only 0.05% of its processing time, even if it switched processors hundreds of times a second (which would imply that its time slices got interrupted after an average of a couple of microseconds).

Really, do you have any performance benchmarks on this? I don't see why switching processors would be anything but completely negligible, well below 1%.

[Ahiga]

Aristocrat, is there any way to constantly specify that assigning of cores to run the game, or to run Windows programs? So that you don't have to do it each time.

[sapi]

Aristocrat, is there any way to constantly specify that assigning of cores to run the game, or to run Windows programs? So that you don't have to do it each time.

Yes.

I think this will do it; if not one of the other Sysinternals programs does.

[Roman Clone]

Ummm, I believe I have a dual Core and My Kotor 2 Ran fine[I cant install it anymore for some reason]

[sapi]

Ummm, I believe I have a dual Core and My Kotor 2 Ran fine[I cant install it anymore for some reason]

There aren't any games that won't run on a dual core...

[Jericho]

Right, the games doesn't need an explicit dual core support. They just has be programmed thread safe.
To use both cores at a time they have to use multithreading but many older games don't use it. This will never add up to 2x2GHz = 4GHz, it will always be 2x2GHz...