Core Clock

[Rienks]

Does the GPU core clock actually matter? What does it even do

[TheRandomness]

It does matter, the GPU core clock is how fast the GPU runs (Please correct me if i'm wrong). For example, a GPU running at 150MHz would perform quite a bit worse than a GPU running at 1500MHz. 

[OAcesync]

Does the GPU core clock actually matter? What does it even do

When comparing different architectures no

[Rienks]

It does matter, the GPU core clock is how fast the GPU runs (Please correct me if i'm wrong). For example, a GPU running at 150MHz would perform worse than a GPU running at 1500MHz. 

So some Radeon with 975mhz clock speed is crap

[TheRandomness]

So some Radeon with 975mhz clock speed is crap

No, any GPU in the range of 900+ is fine. Take the 280 as an example, the reference has a clock of 933~ MHz but when overclocked it can perform as good as some 280x's but take into account what @OAcesync said. (I may be completely wrong in the example... let other people say things)

[Rienks]

No, any GPU in the range of 900+ is fine. Take the 280 as an example, the reference has a clock of 933~ MHz but when overclocked it can perform as good as some 280x's but take into account what @OAcesync said

Oh okay thank you

[SPAS-ID]

Basicly it gave you More Performance

[Naeaes]

If you compare two cards that are of the same generation and architecture, manufacturing process and so on, it matters. Especially if the chips are identical. Basically higher is better. Albeit Core clock isn't everything, what really matters is maximum boost clock but there's no way to determine that without buying a card and testing it in your system. With that in mind it's not wrong to compare core clocks. 

 

If the cards aren't the same or similar enough, comparing clocks is like comparing width with color. They're not comparable. Same goes for CPUs and RAM.