How To Enable All Cores in Windows

Robert Hayes February 1, 2021

The evolution of Central Processing Units, or CPUs, is a fascinating and complex topic to study. From the release of the Intel 4004 back in 1971 to the modern day Intel 10th Series Processors, these chips have seen an astonishing increase in speed and computing power in just five short decades. Computing tasks that were once unimaginable for even the biggest mainframe computers are now able to be handled by the cheapest budget smartphone, with even the most basic of laptops possessing hundreds of times the power of the computers running the Apollo missions. However, even with the astronomically fast advancement of computing power, one development that still puzzles people is the concept of multi-core processors. Manufacturers like Intel and AMD tout their ever-increasing core counts on newer processors – 4 cores, 8 cores, 16 cores, even 32 cores – and their usefulness for heavy computing loads. But what does any of that even mean?

What Are Processor Cores?

A processor core is an independent processing unit on the overall physical processor chip. Each core has its own processing hardware and cache, and is connected to the rest of the CPU through the chip’s shared memory and the system bus. A core is essentially an entire CPU, so a multi-core processor is like putting several CPUs together and having them work in tandem. The reasoning behind having more cores on a CPU is that it can often be advantageous to split computing tasks between multiple cores rather than one massive one in order to allow it to finish more quickly and efficiently.

However, the effectiveness of this technique depends on the operating system you’re running as well as the specific application you’re running; many operating systems and applications used to not be able to take advantage of multiple cores and would, as a result, not see any measurable advantage from the extra cores. However, fortunately, almost all modern operating systems and many resource-heavy programs such as Adobe Premiere are able to take advantage of the extra cores, and as a result, run more quickly and efficiently than they would otherwise.

Closed Up Photo of Black Dell Central Processing Unit

Multi-core processors got their start back in 1996, with the IBM Power4 processor running two cores on a single chip, which was revolutionary for the time. However, software support for this new innovation did not immediately appear. However, starting with Windows XP in 2001, Windows began supporting multi-core operations and many application developers followed suit. As a result, pretty much any resource-intensive software you use today will fully utilize the power of the multi-core processor that you almost certainly have running under the hood.

(Check out this detailed article about multi-core processing for more information. If you’re building or buying a new PC, then a review of this article on what to look for in a CPU might also be helpful. And if you’re interested in the history of processors, of course we have you covered!)

Enabling CPU Cores In Windows

One question we’re commonly asked at TechJunkie is whether you need to do anything in order to make full use of multi-core CPUs on your computer. The answer is that it really depends on the version of Windows you are running. For older versions of Windows, such as Windows XP, you might need to change a system setting in your BIOS in order to get multi-core functionality working. In any newer version of Windows, however, multi-core support is automatically turned on; you can adjust your settings to use fewer cores if necessary to fix a software compatibility reason, but this is exceptionally rare.

Core Settings In Windows 10

If you’re using Windows 10, all of your processor cores will be fully utilized by default if your BIOS/UEFI is set correctly. The only time you would use this technique is to limit cores, whether for software compatibility reasons or otherwise.

Type ‘msconfig’ into the Windows Search Box and hit Enter.
Select the Boot tab and then Advanced options.
Check the box next to Number of processors and select the number of cores you want to use (probably 1, if you are having compatibility issues) from the menu.
Select OK and then Apply.

If you are using Windows 10, the box next to “Number of processors” will normally be unchecked. This is because Windows is configured to utilize all cores whenever a program has the ability to use them.

Core Settings In Windows Vista, 7 and 8

In Windows Vista, 7 and 8, the multi-core setting is accessed through the same msconfig process as described above for Windows 10. It is also possible in Windows 7 and 8 to set processor affinity, that is, to tell the operating system to use a particular core for a particular program. This was useful for a number of things; you could set a certain program to always run on one core so that it wouldn’t interfere with other system operations, or you could set a program that had difficulty running on any core other than the first logical core to use the core where it ran best.

It isn’t strictly necessary to set core affinities in Windows 7 or 8 but if you want to it is simple.

Select Ctrl + Shift + Esc to bring up Task Manager.
Right click the program whose core use you want to modify and select Details.
Select that program again in the Details window.
Right click and select Set Affinity.
Choose one or more cores and check the box to select, uncheck to deselect.

You may notice that twice as many cores are listed than you have. For example, if you are running an Intel i7 CPU with 4 cores, you’ll have 8 listed in the Affinity window. This is because hyperthreading effectively doubles your cores, with four real and four virtual. If you want to know how many physical cores your processor has try this:

Select Ctrl + Shift + Esc to bring up Task Manager.
Select Performance and highlight CPU.
Check the lower right of the panel under Cores.

There is a useful batch file you can create that can force processor affinity for particular programs. You shouldn’t need to use it but if you do…

Open Notepad or Notepad++.
Type ‘Start /affinity 1 PROGRAM.exe’. Type without quotes and change PROGRAM to the name of the specific program you’re trying to control.
Save the file with a meaningful name and add “.bat” to the end. This creates it as a batch file.
Save it to the program install location you specified in Step 2.
Run the Batch file you just made to launch the program.

Where you see ‘affinity 1’, this tells Windows to use CPU0. You can change this depending on how many cores you have – ‘affinity 3’ for CPU1 and so on. This page on the Microsoft Developer website has a full list of affinities.

Should I Enable All Cores in Windows 10?

There is actually some argument about this, although there is a pretty strong consensus among experts that you should use all your cores. There are essentially two points the anti-corers hit on. One is that reducing the power consumption from laptops and PCs would reduce electrical usage elsewhere. The other argument makes a little more sense, and has to do with laptop battery life. I’m going to look at both of these arguments.

The power consumption angle is pretty hard to credit. The reality is that a modern PC’s power consumption can be high over burst periods of time. But it’s also true that those bursts of power still aren’t using that much juice. Even at top power consumption, a Core i7 (currently the winner of the power hog competition among mainstream CPUs) uses only 130 watts. Compare that to a refrigerator at 250 watts. a window AC unit at 1400, and central air at 3500 watts. If you want to save power, turn the AC down a notch and leave your PC running at full blast.

The argument for reducing core usage in order to save notebook battery life (less energy used = fewer charge cycles = that Macbook lasting a few years longer) has some superficial appeal. I’ll admit that given what a high-end laptop can cost, it might make sense to coddle the machine by turning off some cores. However, that goal can be achieved far more effectively and more conveniently by underclocking the CPU a bit. Underclocking means setting the machine’s clock to run slower than normal, which in turn will reduce performance and drastically cut the drain on the batteries. Cores, when they aren’t in use, just don’t burn much power so the savings would be minimal. Underclocking the CPU directly cuts electrical use across the machine, and can actually achieve the goal of longer laptop life.

The processor is the most important part of your computer, so it makes sense to want to push all the cores to their limit. Of course, if you’re still having trouble pushing your device to the performance level you want out of it, you might want to consider upgrading your processor (if you own a desktop) or looking into picking up a new laptop with cutting-edge hardware. Or, if you’d rather attempt to make Windows 10 even faster on your current hardware, check out our definitive guide here.