Hello, everyone! I’ve been doing some research into computer hardware lately, and one thing that I keep coming across is this idea that the speed of a processor, while important, isn’t the only thing that affects a computer’s overall performance. I’m having a bit of a hard time wrapping my head around this because I always thought that a faster processor meant a faster computer. Can anyone explain why this isn’t necessarily the case? I’m really interested to learn more about this!
In: 97
Speaking specifically about cpus, these days it comes down to what you’re doing with the computer that dictates if it will perform well. These days you can buy everything from 4 core through to 96 or more core cpus, all with differing speeds and other specs. But it comes down to what you’re trying to do. Most consumer software is still designed to run on a single core or a small number of cores, so in these cases CPU speed does matter. A CPU with a faster clock speed will run a single threaded application faster (assuming all other components are equal).
But software designed to run in parallel on multiple cores can get away with lower overall clock speed because it has broken the problem up into more parts, so it’s through putting more than the single threaded application at the higher speed.
Adding some real world examples. In recent years one of the best cpus you can get for gaming has been an 8 core CPU with decent clock speed, even though there are 12 and even 16 core CPU options priced above it. That’s because most games can’t make use of that extra cores so there is no point paying for them. However it you’re building a workstation that will do a lot of multitasking, you’ll want more cores with high speed so you can do more.
The other components matter a lot too. Consider how monumental the change in boot speed was going from traditional hard drives to solid state drives. The speed that you can read and write data makes a huge difference in how fast the computer can complete tasks that deal with large amounts of data.
Ram plays a big role too. Some simulation software is bottlenecked mostly be how fast you can move data between CPU and RAM. And a computer with more memory channels will run a simulation faster than a computer with a higher clock speed but fewer memory channels.
All of that is a long way to say that you need to match computer specs to the tasks you want to do.
Thats like asking why a brain isnt the only factor in how a human performs. It brain is in many ways the same as the cpu bar the fact that the memory is seperate from the cpu and the brain is like an all in one cpu/memory combination.
The brain needs nearly all the organs to function properly. If the liver or kidneys fail , if your circulation is bad , if 100 other things are off the brain functions will be affected. The cpu needs good conections and a good motherboard , hard drive , grapics card etc.
The most important is the connectivity and as the old saying goes, you are only as strong as your weakest link.
Imagine you’re moving, and you’re the sole person in charge of putting things in boxes, but you can’t leave the room (the CPU). Even if you’re super fast at putting items in boxes, there are a couple of bottlenecks:
* How quickly can people bring things into your room to pack (Hard drive to RAM read speed)
* How much space is in the room for people to bring stuff in (Amount of RAM)
* How long your arms can reach before you have to get up and move (CPU Cache)
* How long it takes for people to go around the house to find stuff (Hard drive access speed – less of an issue nowadays with SSDs)
* How efficiently you stack/fit the items in the box (processor architecture)
* The number of people available to take the packed boxes and put them into a truck (GPU bandwidth)
* How quickly those people move (GPU speed)
* The size of the truck (GPU RAM)
MHZ/GHZ doesn’t matter as much anymore because
* modern processors do a lot of stuff per cycle and how much stuff they do per cycle is way more important than number of cycles per second.
* the memory and other components operate at their own speeds which are often much slower than a very highly clocked cpu- so being super fast can just mean you wait more. A huge amount of CPU performance comes down to finding stuff for the CPU to do while it is waiting on memory.
#ELI5
Your car has the highest-horsepower engine that money can buy. Vroom vroom!
But you put the [smallest possible wheels](https://cdn.motor1.com/images/mgl/XeoVl/s1/renders-of-cars-with-tiny-wheels.jpg) on your car.
Does that analogy help?
What good is all that horsepower if the wheels are so tiny that you can’t go fast?
A computer is more than just a processor. The processor speed matters, for sure, but:
* Data has to get TO the processor. How fast is the conduit to the processor?
* Data has to get out FROM the processor. Again, how fast is the conduit?
* How FAR is the conduit? One reason computers have gotten faster is because the distance between the processor and other things is very small. Less distance to travel means faster travel time.
* You need memory, and its speed matters too. Also the amount of memory.
* You need a hard drive too. What if your hard drive can’t read/write very fast?
Putting the strongest engine in your car, is meaningless if you have itty-bitty wheels. Also meaningless if your air intake is too small and not enough air gets to the engine. Also meaningless if the transmission isn’t built to handle all that horsepower.
Similarly, the processor is just one component of a system. Beefing up one part of the system doesn’t necessarily mean the entire system will be better.
I’ll try a real ELI5.
The processor is like a really fast mathematician sitting in a room and calculating stuff. You can bring him math problems and he will solve them for you. The faster the mathematician the better.
Until the mathematician is so fast that the door to his room is not wide enough to bring all the problems to him and collect all the solutions. Then it makes no sense to hire an even faster mathematician, you need to build a bigger door first.
How wide the door needs to be depends on the problem. If the problems are easy the matematician solves them quickly and needs more problems per hour delivered to him. If the problems are hard, you don’t need a door that wide. This is why the optimal configuration of the PC depends on the type of programs you usually run.
The CPU handles general processing tasks. Microsoft word, your web browser etc. That’s being ran on your CPU and the faster it is the faster it will process those programs. However there are other things to consider like RAM, which you can think of as the “desk space” your computer has to work with. When your computer runs out of desk space it has to stick some things in its filing cabinet(the hard drive/ssd) and pull it back out later. This slows things down so it’s better to have as much desk space as you can afford. This is before getting to things like video games, autocad, and photoshop, which all use a graphics card because graphics cards have their own processor and memory that are designed to efficiently process the kinds of mathematics used in visual/graphical calculations.
A processor does work more or less as fast as the work gets to it. Modern processors are really, really fast. The issue is that it is so fast, it sometimes runs out of work.
Imagine if the parts in the computer are all connected by conveyor belts. All the parts want to send their stuff to the CPU to get worked on, but if the conveyor belt going from one part (system memory, for example) is slower than the processor is working, then it can’t get work to the processor fast enough.
Computers have 5 basic parts: input devices, processor, storage (both RAM and hard drives are included), output, and a backbone that connects the former 4 together. Each of these have differing capacities and maximum throughput, and they all have to work as fast as the slowest element.
The processor speed is like how many times you can swing a hammer per minute. But someone might hit harder with each swing and so does more work with less swings. This is the equivalent of processors that are able to accomplish more with each cycle. Also, you might get more people to swing their own hammers with you, this is like a multi-core processor.
But maybe you’re hammering in nails and they guys putting the nails in place is going slow. This is like a bottle neck with computers where another component is slowing it down (RAM or Hard Disk for example).
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