What is the difference between these two, and under what circumstances would I want to implement them? Are there circumstances when I would only want 1 and not the other?
According to Wikipedia, hyperthreading is a proprietary Intel technology, whereas overclocking seems to apply to any CPU (Intel or other).
But still, they both seem like very similar ways of speeding up processing time on the same machine, and I wonder if they are synonyms or mutually-redundant.
Two completely separate approaches to increase performance.
Overclocking is the process of tweaking motherboard (or graphics cards) settings to have the 'clock' run faster than the vendor certified. Can increase performance for single or multiple threaded scenarios. Also has risk because excess heat can be generated which can damage circuitry.
Hyperthreading is a way to present one core to the OS as if it were two cores (see What is hyper-threading and how does it work??). This allows the OS to run two threads on a single core, somewhat simultaneously. In reality the hypervisor causes the core to switch between threads very rapidly. This can increase performance in some multi-threaded scenarios. Also there is no risk to this approach like there is with overclocking. but as noted an Intel only solution.
They are not mutually exclusive. You can overclock a hyperthreaded CPU.
Hyperthreading (HT) is more threads. Overclocking is more processor speed.
Overclocking is more useful and practical for gaming applications as opposed to hyperthreading. HT is more useful for editing or rendering of say media files because it allows multiple pieces of software to run at the same processing speed instead of dividing.
Overclocking is better for games because it is one application running as opposed to multiple and can take advantage of the boosted performance of the processor.
