Cores? Dual core, Quad core... What's the difference?

[gp792]

Hi guys,

I have a question relating to cores. What is the difference between dual cores @2.5GHz and quad cores @2.5GHz? My gaming laptop has quad cores @2.5GHz (with Turboboost up to 3.2GHz), and I wanted to know what dual core and quad core really is. The reason I ask this, is because I saw a game with dual cores @2.5GHz as part of the minimum system requirements, and wondered if that would cause a quad core i7-4710MQ @2.5GHz to struggle, or not?

 

[shaneturner12]

It's all to do with how many processors are on the one chip - quad core has 4 whereas dual core has 2. However, a quad core is not twice the speed of a dual core running the same clock speed due to the way the processors are used by the operating system.

Shane

 

[gp792]

It's all to do with how many processors are on the one chip - quad core has 4 whereas dual core has 2. However, a quad core is not twice the speed of a dual core running the same clock speed due to the way the processors are used by the operating system.

Shane

So, is there any difference beside the number of cores?

 

[shaneturner12]

There may be other differences, but I will let one of the more hardware-oriented users on here cover that.

Shane

 

[johnwhelan]

It's simpler to put all the program instructions on a single thread and that's what used to happen in days long gone by. The CPUs were single core and just executed a single line of instructions. Floating point co processors came along and the CPU would pass over the instructions to be executed to the floating point unit, and later a separate processor processor was added to process the video instructions. These later became known as GPU or video cards.

Single core processors hit the heat barrier, and so some bright spark thought up multiple cores. The only problem with them was they had to be fed program instructions. Now you get into semantics, sometimes these are called threads some times something else but the basic idea is that the program instructions have to be packaged so they run over multiple cores. The easy way is use the operating system and run one program on one core and another on a separate core.

TRS2004 ran one one core, TS2009 driver used a maximum of two according to perfmon. Even if the program only uses two cores there can be an advantage as the operating system can sit on another core. The programming problem is one bit of program has to wait until the other core is finished.

So your game may or may not use more than two cores, then you add in Intel hyper threading which is a way of keeping all the bits of the CPU running to get the most throughput. So my quad core actually shows eight cores to the operating system ad all being utilised when CM is running.

Then we come back to the heat problem, the quad core processor have better cooling than the dual core processors so if one or more cores aren't being used they are shut down. This gives more cooling capacity so many quad processors will actually overclock very slightly to run faster than 2.5 whatevers.

Now having said that the real bottleneck on a CPU is rarely processing instructions, its getting the information into and out of the processor. Caches help here, but over time you can spot which instructions get used more often and you then modify the processor to favour these instructions. So that means a 2005 2.5 processor is not as fast as a 2015 2.5 processor even though they are rated the same. tomshardware benchmarks are probably the place to compare them.

In simple terms a quad is usually faster than a dual core of the same speed but if you are comparing AMD quad to Intel and the Intel is dual core with hyperthreading then things might not be quite so simple depending on the software being run.

Aren't you glad you asked?

Cheerio John

 

[gp792]

It's simpler to put all the program instructions on a single thread and that's what used to happen in days long gone by. The CPUs were single core and just executed a single line of instructions. Floating point co processors came along and the CPU would pass over the instructions to be executed to the floating point unit, and later a separate processor processor was added to process the video instructions. These later became known as GPU or video cards.

Single core processors hit the heat barrier, and so some bright spark thought up multiple cores. The only problem with them was they had to be fed program instructions. Now you get into semantics, sometimes these are called threads some times something else but the basic idea is that the program instructions have to be packaged so they run over multiple cores. The easy way is use the operating system and run one program on one core and another on a separate core.

TRS2004 ran one one core, TS2009 driver used a maximum of two according to perfmon. Even if the program only uses two cores there can be an advantage as the operating system can sit on another core. The programming problem is one bit of program has to wait until the other core is finished.

So your game may or may not use more than two cores, then you add in Intel hyper threading which is a way of keeping all the bits of the CPU running to get the most throughput. So my quad core actually shows eight cores to the operating system ad all being utilised when CM is running.

Then we come back to the heat problem, the quad core processor have better cooling than the dual core processors so if one or more cores aren't being used they are shut down. This gives more cooling capacity so many quad processors will actually overclock very slightly to run faster than 2.5 whatevers.

Now having said that the real bottleneck on a CPU is rarely processing instructions, its getting the information into and out of the processor. Caches help here, but over time you can spot which instructions get used more often and you then modify the processor to favour these instructions. So that means a 2005 2.5 processor is not as fast as a 2015 2.5 processor even though they are rated the same. tomshardware benchmarks are probably the place to compare them.

In simple terms a quad is usually faster than a dual core of the same speed but if you are comparing AMD quad to Intel and the Intel is dual core with hyperthreading then things might not be quite so simple depending on the software being run.

Aren't you glad you asked?

Cheerio John

John,

so it is faster then, correct? My quad core is a Haswell (I think), so if a game's minimum specifies dual core Haswell at 2.5GHz, while mine is quad core at 2.5GHz; but the recommended is quad core at 3.2GHz, will that be a problem? I know the game in question is not Trainz, but this question is more or less about cores and system requirements, since I do not know much about these things.

 

[johnwhelan]

John,

so it is faster then, correct? My quad core is a Haswell (I think), so if a game's minimum specifies dual core Haswell at 2.5GHz, while mine is quad core at 2.5GHz; but the recommended is quad core at 3.2GHz, will that be a problem? I know the game in question is not Trainz, but this question is more or less about cores and system requirements, since I do not know much about these things.

Then you get into is it a laptop or desktop? Laptops are designed to conserve battery life, desktops more for performance, screen size will have a big impact, a 600 by 800 screen needs less muscle than a 2560 x 1440 one.

However if they say a dual core 2.5 will work and you have a quad of the same speed then you may assume your performance will be better than the dual. If they recommend a quad at 3.2 then you may assume at least that it is programmed to take advantage of all four cores.

http://www.pugetsystems.com/labs/articles/Haswell-Core-i3-vs-i5-vs-i7-Which-is-right-for-you-475/

Cheerio John

 

[gp792]

Then you get into is it a laptop or desktop? Laptops are designed to conserve battery life, desktops more for performance, screen size will have a big impact, a 600 by 800 screen needs less muscle than a 2560 x 1440 one.

However if they say a dual core 2.5 will work and you have a quad of the same speed then you may assume your performance will be better than the dual. If they recommend a quad at 3.2 then you may assume at least that it is programmed to take advantage of all four cores.

http://www.pugetsystems.com/labs/articles/Haswell-Core-i3-vs-i5-vs-i7-Which-is-right-for-you-475/

Cheerio John

Thank you John,

My laptop has turboboost up to 3.2GHz, but I'm wondering if that will cause serious issues over time? The reason I had such a question, is because everything else (Graphics card, RAM, etc) are perfectly fine, if not better than the recommended specs; it's just the processor that has me worried. When it comes to Trainz, that other train sim, War Thunder, World of Tanks, Heroes & Generals, etc., my computer is perfectly fine. If an upgrade is needed, I presume that a more powerful processor shouldn't be too expensive, right? Would I need to upgrade anything else, if I chose to upgrade the processor?

 

[johnwhelan]

Thank you John,

My laptop has turboboost up to 3.2GHz, but I'm wondering if that will cause serious issues over time? The reason I had such a question, is because everything else (Graphics card, RAM, etc) are perfectly fine, if not better than the recommended specs; it's just the processor that has me worried. When it comes to Trainz, that other train sim, War Thunder, World of Tanks, Heroes & Generals, etc., my computer is perfectly fine. If an upgrade is needed, I presume that a more powerful processor shouldn't be too expensive, right? Would I need to upgrade anything else, if I chose to upgrade the processor?

You have to be very careful when upgrading CPUs on laptops. Laptops are designed to tight limits and running a warmer CPU can push them. Most software runs the CPU about 3-5% of the time Trainz will run two cores at close to 100% so many machines than will work with practically anything else will over heat with Trainz. If your manufacturer offers different CPUs as options and you aren't on the lowest then you could drop in a faster one. It's not a job I'd personally tackle.

Trainz depends more on the content you're running than anything else. Some content doesn't take much machine resources, some are killers. There are some sketchup created scenery objects that will kill the performance even on the fastest machine. Some locos are 7,000 polys, have lod and look good others that look much the same are 39,000 polys and don't have lod, content creators vary in their ability to create good looking assets with low machine impact. Run twenty wagons the same fine, but twenty mixed wagons will have a much bigger impact which is why its difficult to say if a machine will run Trainz well.

Personally I'd buy a desktop for Trainz. Having saud that many are happy with the performance in Trainz, you have some control with the slider options, if drop the draw distance down then less resources are needed for the same frames per second. At the moment I'd wait and see how TANE unfolds, it requirements may be different, it will almost certainly be happier with more memory and using directx11 might even get more performance out of your existing hardware.

I think you're back to the empirical method, or suck it and see what happens.

Cheerio John

 

[stouthm]

Huh?? What the heck did John just say? Love your answer John even though I'm not sure what you said.

 

[johnwhelan]

Huh?? What the heck did John just say? Love your answer John even though I'm not sure what you said.

In the chem labs sometimes if you wanted to know if something was poisonous one method was called suck it and see. The empirical method is sometimes used when you don't have enough information, you just try it. Depends on cost etc but often it can be the cheapest method.

Cheerio John