How does frequency on a CPU impact performance? I.e. if I overclock a 2Ghz CPU to 4Ghz, is it +100% performance?
In: Technology
It would allow the CPU to do CPU things twice as fast.
It doesn’t make your RAM twice as fast. It doesn’t make your disk twice as fast. It doesn’t make funny cat pictures download twice as fast.
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No it’s not a linear increase like that.
Personally though I find clock speed to be the best indicator of performance apart from maybe benchmarks. Like others have said, a faster clock speed means that the CPU can process more instructions in less time.
There are other factors though like cache size (the more data you can hold in cache the less fetches you need to make from main memory – and fetches are very costly in terms of performance).
Another factor could be the instruction set being used, essentially you get simple instructions such as ADD which takes the values in 2 different registers, adds them and stores the result in a third register. We’re getting a bit outside my area of expertise now but let’s say the ADD instruction can be completed in a single clock cycle.
Now lets imagine an instruction set which contains a multiply instruction which can complete in 2 clock cycles. And imagine we want to multiply 8×7.
How many ADD instructions does the first simple set need? Maybe 7.
How many MUL instructions does the more complex set need? Let’s say 1.
In these examples, we could say that a CPU with lower clock speed using the more complex instruction set might actually have better performance. To be clear, I’m not arguing that complex instruction sets are inherently superior, only in this made up example I’ve given.
In summary, it’s a balancing act, but for consumers I’d generally state that clock speed is a good indicator of performance.
Woof, an ELI5 that I can finally answer.
At the most simplistic level, there is no concrete percentage of impact. Increasing the clock speed by %100 (besides being a very bad idea) will not increase the performance by %100. Different CPUs by different manufacturers will always be different in how much improvement you get from overclocking.
In a more in depth sense, there is a point of diminishing returns, which depends on the load you have, the manufacturer, all sorts of different factors. Eventually you’ll reach a point where the excess heat created is so much that your CPU will in fact slow down, as heat creates resistance to electricity. Usually, though, the CPU will have a component failure long before that.
I can go more in depth if you like about certain aspects, but this subreddit is about simplicity. I hope I answered your question!
Increasing the clock speed on a CPU increased the frequency with which it can process tasks. If you double its clock speed, that means it can send data through the bus twice as frequently.
This, however, does not translate to twice the overall speed of the computer. There are a number of other links to the chain that would bottleneck things (speed of your RAM, volume of RAM, speed of the other components within (GPU, SSD, etc), but in theory a task that relies 100% on the processing power of the CPU could be performed in half the time (think of highly complex mathematical calculations).
BUT! Increasing the clock speed is not without consequence. Faster clock speeds generate more heat, and without effectively dissipating that heat (with a more efficient heat sink/fan configuration, or liquid cooling) that resultant heat will slow the machine back down. (hot wires have higher electrical resistance). If the components get TOO hot they’ll actually stop working altogether, as the resistance gets too high for the circuit’s integrity to be maintained (or it could result in physically damaging/destroying internal components like resistors, capacitors, melting solder points, etc.)
Generally overclocking your CPU is limited to a 5-15% increase, and is only done by enthusiasts who have invested in good heat management (a high conductive heatsink with push/pull fan setup, or liquid cooling.)
In short: heat is the enemy of performance in a computer, and increased clock speed, while results in increased performance, also results in increased heat which is bad. So it’s a balancing act to get the most bang for your buck without shortening the life-span of the components themselves.
EDIT: I accidentally a word
pretend you can only work on cleaning your room when your friend Billy comes over. He doesn’t come over very often so you can’t work on cleaning your room very often, so it takes a long time to clean your room.
Now imagine that he can come over once a day. You can get your room cleaned even faster now.
Now imagine that he can come overo 10x a day. Your room is going to get cleaned up much faster now!
CPU frequency works the same. A computer can only do 1 tiny piece of work every time its clock ‘ticks’. The amount of work it can do in a ‘tick’ isn’t much, so the faster the clock ‘ticks’, the faster the computer can get work done.
The clock’s frequency is measured in this thing called ‘hertz’ (denoted ‘Hz’) that means ‘how may times per second’. so 10Hz means ’10 times per second’.
GHz means “billions of times per second”. So a 2GHz computer can literally do 2 billion things a second. a 4 GHz computer can do 4 billion things per second – literally twice as many things.
THat’s why a 4GHz computer is much faster than a 2GHz computer.
Imagine if you could double the speed of your car. In an ideal world you could get to work/school in half the time. However, in the non-ideal, real world, there are things that prevent that such as speed laws and the other drivers that obey them. Even if other drivers don’t observe speed laws your tires are likely not up to doing twice the legal speed limit all the time, Your engine will get hotter and the oil will break down faster. The answer is it will make your computer faster but things like hard drive access, reads and writes to RAM, video rendering etc. will all stand in the way of the ideal.
In a nutshell your cpu does one thing every time the clock ticks. 2Ghz is 2,000,000,000 ticks per second. Increasing clock speed means doing more stuff per second.
Quick question, why don’t we use air conditioning/refrigeration technology for cooling PCs? The efficiency and cooling should be a no-brainer right?
It theoretically is, yes. Double the speed is double the calculations made. However, every other piece of hardware outside of the CPU may not be able to handle it and will throttle the results back, depending what you’re doing. Basically the CPU will generate a new result so quickly that when it knocks on the door of another asset – they’re still busy. The easiest case to understand is a traditional HDD with a platter. It’s fairly easy to generate more data than an HDD drive can write. This is true for everything else, in increasingly complicated ways – a PC is the collection of a lot of moving parts and the CPU is just one component.
Right now CPU’s are in a state that they are less often the bottleneck to performance than they were in the past. So upgrading your CPU tends to yield less beneficial results unless you’re specifically running programs that bend the CPU over hard.
For general gaming the GPU is holding up the show more often than not. If you’re running commercial/design software then you still can benefit greatly from overclocking the CPU, but you need fast and sufficient RAM, and disk writing capability paired up with it.
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