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Ghz and Core Speed Confusion

Drifty_Child

Drifty_Child

macrumors member
Original poster
Dec 12, 2017
85
7
USA
Hi, I'm a noob when it come to hardware. Would a MBP with quad-core and 2.6ghz be slower than a MBP with 6-code and 2.2ghz? How can I know by looking at the numbers?

Edit: For reference, I am a game designer, using Unity and adobe products, and I'm trying to compare the 2018 MBP with my current 2012 model.
 
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With multi-core processors, it will depend on how they are architected. Many things come in to play with how fast a computer will operate. Processors are one thing. Memory and it's speed, video and it's memory/speed and the thing that ties it all together is the bus speed. You can have the fastest components but if the bus speed is low, they will be limited in their potential.

But to answer your question specifically, the 6-core i9 will be faster than the 4-core i7. The 15" has more space for many things and will be the more powerful machine. If, however, the 13" is more affordable and works with what you are looking to do, nothing wrong with it.
 
Thanks for the rundown. Actually, I'm trying to compare the 2018 MBP with my current 2012 MBP, which has the 4-core i7.
 
Drifty_Child said:
Hi, I'm a noob when it come to hardware. Would a MBP with quad-core and 2.6ghz be slower than a MBP with 6-code and 2.2ghz? How can I know by looking at the numbers?
Click to expand...


The current offerings will all be perfectly sufficient. CPU's are so fast in today's world you'd really only notice it if you're doing inetensive tasks using professional programs such as Adobe using a stop watch. Even then the faster, more expensive options would only shed seconds, or minutes off practical render times. For average use you will not notice a difference. Even in games the difference would only be single didget frame rate changes for practical purposes.
 
Getting a clear idea on CPU performance isn't the easiest thing, but you'll get some idea from in depth CPU write-ups like AnandTech does...

Firstly, when comparing across generations you'll need to factor in IPC (instructions per clock) improvements. IPC is the measure of how many instructions the CPU can execute per clock cycle. In very simple terms a CPU that can do 2 IPC would be twice as fast as one that does 1 IPC at the same clock speed.

Second, you'll need to have some handle of your workflow to know how well your workflow spreads across multiple CPU cores. Not all applications do well on multiple cores and many struggle to use all cores well. This is very important due to the way modern CPUs are designed and marketed. Intel and computer manufacturers tend to market the CPUs "turbo clock" which is the speed the CPU can hit if it can turn off all except 1 core and has the thermal headroom to do so. As a result, you'll generally see better performance on a higher clocked CPU if your workload is heavily single threaded, but you can see better performance on a slower CPU with more cores if your workload scales well across more cores.

It gets more complex than this, but this should help give you a starting point.
 
Synthetic bencharks can give you an idea of how much faster a CPU is, but if you don't fully untilize the CPU it can be a whaste of money to spend on.
 
darksithpro said:
Synthetic bencharks can give you an idea of how much faster a CPU is, but if you don't fully untilize the CPU it can be a whaste of money to spend on.
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True. The 2018 will also have faster memory, faster SSD, faster connectivity (TB3), faster wifi, faster USB, faster GPU etc. It's way more than just a CPU upgrade.
 
Yeah, absolutely no competition, even if base clock speed is slightly slower, it's several processor architecture updates newer and will be noticeably faster even in single core.
 
Drifty_Child said:
Would a MBP with quad-core and 2.6ghz be slower than a MBP with 6-code and 2.2ghz?
Click to expand...
Good question, its not a noob question and its not cut and dry any longer.

GHz (or back in the day MHz) was the measure of how fast a CPU executed a single instruction. So a 2.6GHz would execute a instruction 2.6 billion times a second. That would have course out pace the 2.2. There's more to that now adays because of peeking, prefetch and other advances, so cycle rate (the GHz) is a poor indicator of performance and speed.

Core, is the number of CPUs or brains on the piece of silicon, now you're comparing 4 brains to 6 brains, but not all apps are written to taken advantage of that many cores and there's still many applications that will just execute single threaded, i.e., use one core.

Some applications may very well seem a tad faster on the 2.6 quad core vs the 2.2 hex core, but the speed difference will be so slight, you'll not notice imo. Additionally you're better off with more cores as you can multitask more efficiently. I only mentioned running a single app, but most people have multiple programs running and so in nearly every typical use case the hex core processor will outpace the quad.
 
Drifty_Child said:
Hi, I'm a noob when it come to hardware. Would a MBP with quad-core and 2.6ghz be slower than a MBP with 6-code and 2.2ghz? How can I know by looking at the numbers?

Edit: For reference, I am a game designer, using Unity and adobe products, and I'm trying to compare the 2018 MBP with my current 2012 model.
Click to expand...

In basically all cases the 6-core will be faster, because those clock speeds aren't actually what the CPU can run at.
If you just had a 4 core locked at 2.6Ghz and a 6 core locked at 2.2Ghz then it might be true that in some cases the quad core is faster.

But what ignorant people don't realize is that if you run a program that can only use 4 cores, the 6-core CPU will be able to run at higher clock speeds than specified.

Also the best performance metric for regular folks is price, the more expensive it is the faster it is. Don't overthink it.
 
My work also involves adobe products and unity. I went from the 2013 quad 2.6ghz to the 2018 hex 2.6ghz.

For “sit and wait tasks” like rendering or compiling, you’re looking at just under a 2X speed up.

For actively working, the experience does not feel appreciably different, mostly because everything was already pretty responsive on the 2013 machine.

With the exception of the graphics card for game engine stuff. With the 2013 model i ended up doing most in-engine stuff on a windows desktop because the MacBook Pro was too sluggish in any project more complex than a mobile game. Sadly the 2018 didn’t really improve this in any meaningful way.

Supposedly the new Vega options might make more of a noticeable difference. Wish I’d known those upgrades were so close were on the horizon and I’d have held off my purchase a month. Only consolation is that external gpus offer some sort of (expensive) upgrade path for that situation.
 
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