4 threads vs 8 threads (same cores, same speed)

[Sintexis AMP]

What's the difference?
Is it worth to go for 8 threads over 4?

 

[grmnlxndr]

Considering they are same architecture, each core should perform equally. So having 8 threads will have double performance.

But, if you compare using SMT (hypertreading) and not using, you will have a performance increase but not double.
Also you cannot compare directly different architectures, like Zen and Core.
In my opinion, just look for information to compare both CPUs to see how they perform in different workloads.

Best Regards

 

[Compuser10165]

By same cores do you mean the same architecture and also both cpus are 4 cores, but one has 8 threads vs 4. That is the typical i7 vs i5 question. It depends on what you do. If gaming is you intent, than it would be more beneficial to invest the extra money in a faster gpu than pay the extra price for a 4 core i7. However, the i7 will perform better in some games and almost the same as an i5 in others provided you have a capable gpu paired with the cpu. If you want to buy now and you want to mostly game, I suggest getting an i5 7600K or i7 7700K (with K series you can easily overclock).

 

[boosted1g]

Depends on what CPU you are looking at, depends on what purpose you are looking at.

If you are looking at say an fx8350 cpu (so 4core/8threads) vs a 7th gen i5 (4core/4thread) then the i5 is still better because of the much newer archeticture which has better IPC and is much more efficient.
Now looking apples to apples the 7th gen i5 vs 7th gen i7 the i7 is going to clearly be better but that only matters in programs that can utilize the extra threads. If you are doing office applicaitons and web browsing the i7 will give you noghting but $100 lighter of a bank account; if you are doing well threaded applications like photoshop or handbrake it will make a large diffference.

 

[geofelt]

Worth is something only YOU can determine.
If your use is for multithreaded enabled production apps, then 8 threads is best.
But, if your usage is for gaming, then there is little value in having more than 4 threads.
Most games can effectively use only 2-3 threads.
For games, single thread performance is more important.

 

[Solandri]

Hyperthreading (running two threads in one physical core) works by letting the second thread use parts of the core which aren't being used by the first thread. But the thing is, if a computing task is CPU-bound, it's usually because a specific part of the cores (say, the floating point arithmetic unit) is being fully used. The second thread won't be able to use that part of the core because the first thread is already using it, so there's little to no benefit to running a second thread on the core.

So for hyperthreading to be effective requires a very diversified task set where different threads need different parts of the CPU simultaneously. In terms of common real-life tasks, this happens most often in video encoding/rendering, and data compression. If you do these tasks a lot, the hyperthreading on the i7 is definitely worth it. Some of the newer games can effectively use hyperthreading, but you really need to check on a game-by-game basis because other games won't even use all 4 cores.

Outside of these real-life tasks, you're going to see limited benefit from 4 cores + hyperthreading vs just 4 cores and no hyperthreading. Maybe about a 10%-20% speedup, instead of 50%-70%. And the extra $100 cost of an i7 over an i5 would be better spent buying a faster i5.

 

[synphul]

It sounds like a comparison of an i5 vs i7 at the same clock speed from the same generation. If so, ht can help improve performance but not by double despite double the threads. It can vary depending on the application, there's no clear cut 'it will absolutely offer xyz% performance'. It could be the same, less performance, more performance. Usually it's more but typically around 5% up to 15-20% improvement.

Hyperthreading doesn't add cores, it changes the way the same 4 cores process the data and makes it more efficient. Less pauses in the processing if one thread has to wait for other data in order to be processed. It helps to know what the intended use will be in order to speculate on whether or not it's worth it.

Are big tires worth it for a truck? No telling, is it 4x4? Will it be used for offroad driving? If so, maybe. Is it just for driving around in the city on flat streets? Probably not, it's not needed and provides no advantage, if anything it will cost more and hurt gas mileage.