i3 vs i5

[StrandedonEarth]

I read somewhere in these forums that the i3 is better than the i5 for KSP. If so, could someone explain why please? thanks!

[Camacha]

I read somewhere in these forums that the i3 is better than the i5 for KSP. If so, could someone explain why please? thanks!

I cannot comment on the intentions and reasoning of others, but I assume it is because the i5 has more cores and KSP only uses one. The caveat is that processors generally get used for more than KSP and that Unity might use more cores in the future. Oh, and that Ferram made a mod that enables a form of multithreading.

[Red Iron Crown]

KSP is already multithreaded, it's just that the framerate-limiting physics is single-threaded so the game behaves like a single threaded app. Sadly, it is likely to still behave so if multithreaded physics makes it into Unity; at best we can hope for a thread per craft in the physics bubble.

I wouldn't go so far as to say an i3 is better than an i5, other than in the performance/price metric. They're all Haswell cores, so an i3 clocked the same as an i5 should perform almost identically (there are some features disabled in i3s, but none of them matter for KSP). Because a given clockspeed is cheaper in an i3 than in an i5, that means the i3 offers more performance per dollar. That said, if you don't mind overclocking, the Pentium Anniversary Edition is the current champ in single thread performance per dollar. This ~$80 processor has no single thread performance equal until you spend almost three times as much for an unlocked i5.

All this only applies to loads that are single-thread bound; if any of the other things you use the PC for are multithreaded or you do multiple CPU-heavy things simultaneously (like play KSP and record it or stream it), that Pentium will be outperformed by the i3, which will in turn be beaten by an i5, which will be outclassed by an i7.

[Camacha]

which will in turn be beaten by an i5, which will be outclassed by an i7.

This is not necessarily true. The hyper-threading of an i7 has a somewhat strange pattern of gains and little to no gains. The very nature of the technology, where only a small portion of the core has been executed twice so that the OS sees two where there is in reality one, makes it different from just higher clocks or more cache. On average you will see a gain of somewhere between 5 and 10%, but that is distributed between no gains or even losses in some cases, while providing a 20% gain in other cases. It very much depends on the workload whether the hyper-threading helps anything. There are a few specific workloads that have a lot to gain - rendering, video editing and virtual machines for example - and a lot that make little to no difference. Gaming, unfortunately, is a workload that typically barely benefits and HT has been known to even slow down games compared to chips without the feature.

That is why I generally say that if you cannot explain specifically why you would need an i7, you don't need one. Changes are fairly big you would never benefit from what it has to offer.

[Red Iron Crown]

I agree Camacha, hyperthreading is a bit of a strange bird. As I understand it, it allows a thread to run concurrently with another on the same core that doesn't use the same execution units; e.g. a floating point-heavy thread alongside an integer-heavy thread. The cases where you're pegging the CPU with two types of load are pretty fringe, a user is almost always better served with a cheaper, higher-clocked i5.

[StrandedonEarth]

Ah, that's the part I must have forgot: Bang for the buck, always important for Kermanity. Thanks!

[Camacha]

I agree Camacha, hyperthreading is a bit of a strange bird. As I understand it, it allows a thread to run concurrently with another on the same core that doesn't use the same execution units; e.g. a floating point-heavy thread alongside an integer-heavy thread. The cases where you're pegging the CPU with two types of load are pretty fringe, a user is almost always better served with a cheaper, higher-clocked i5.

I think hyper-threading is best explained as allowing the core to switch tasks quicker, so that idle time is reduced. This means that in tasks that mean a lot of switching, like rendering, gains are substantial because they add up. You do not really gain any calculative power, you just utilize it more efficiently.

[Elthy]

If its just for KSP you are better of with an i3 (i assume you are talking about desktop CPUs, mobile is very differnet) if it comes to Bang/Buck. But if you want to play some other modern games (think of the ones that are released in 2-3 years) you should buy an i5. With an i5 you wont have to upgrade for a long, long time...