Alright, so, as you can perhaps tell by my title, I don't really know, but I know it's about either one, as it pertains to one question I have. I love PC gaming, but I'm not the most well-versed in everything that goes on inside my PC. My question is, I want to get the most out of my PC, and I'm not entirely sure if turning on all cores, or processors does anything, or if they already turn on when you play games. I typed in msconfigs, went to system configurations, selected boot - advanced options, and checked number of processors; I put four. I then had to restart my computer. Now, I don't actually know how many processors I have. I checked in my task manager under performance, and it says cores two, and four logical processors. Did I select the correct amount of processors? Also, does this do anything for my computers performance? I have an Intel(R) Core(TM) i7-2670QM CPU @ 2.20GHz if that helps any. My PC isn't a great gaming PC; in fact it's not even a gaming PC, but I try to play what I can. I got it for free a couple of years ago from work, and was surprised by how good it was. I was asked whether I wanted it before even seeing it, and I said "Um... I guess so?", expecting to regret it later, where it'd sit there waiting to be thrown out. That turned out not to be the case as it's what I'm still using, as I type this now even. Anyways, hopefully someone can help. Thanks.

You should have 4 core and 8 logical processors with that CPU, your PC should be using all of them by default, so you setting it to 4 reduced your maximum performance by half. You should go back in and change it back to 8, or set it to default.

@lassieme: Cool, thank you!

In case you're curious, here's what's actually going on:

A CPU "core" is a mostly-independent processor embedded in the same die (aka chip). Since you have four actual cores, your computer has four times the processing power of a single core. Simple, right?

Almost. The fact is that a single piece of code can't use all four cores to do the same task. If you want to use the full power of a CPU, you need to break up your program to do multiple things in parallel. Then, each core can work on a different task. However, not all programs can do this easily. Things like video encoding or compiling programs can do this, because the task lends itself to being broken up into chunks. Other things, like video games, are less able, since the game needs to do everything in sequence, and each frame is based on the one that came before it. These programs can only use a single core at a time. Most programs are like this.

So, the upshot is that your computer can effectively run four programs at the same time.

There's one additional wrinkle. The i7 line of processors supports a technology called "Hyper-Threading". A Thread is a task I mentioned above. Hyper-Threading (H-T) allows a single core to swap between two distinct tasks very quickly. Normally, there is a (relatively) large overhead to switch from one task to another, but H-T allows the core to quickly save all the data it was working on and swap it for a different set, like two different hot bars in an MMO or something. While this doesn't actually allow the core to do two different things at the same time, it does mean that it's spending less time swapping tasks, and more time actually doing stuff.

This capability gets expressed as "Logical Processors" in Windows, which is why it shows should show 8 of them.