How fast a PC must be?

[Jaeleth]

Hi.

I haven't stumbled into serious lack of speed problems until I decided to put together a huge space station, together with tow ships, manned ships, a fleet of probes and so orbiting EVE and all within a few tens of meters to hundreds of meters of each other totalling around 1200 part count...

I noticed the graphics card is not that significant, I quadrupled the graphics card memory and switched from a reasonable older one to a more recent model with not a significant change in frame rate. I have only 2 mods, mechjeb, and alarm. I kept the same processor and memory.

I think that processor speed is more important than graphics capabilities when dealing with large a large part count. As for memory, I have 6 GB.

I'd like to know from you which item you consider most important in improving frame rate with high part count: graphics, memory, processor

And also to know if, above a certain part count, there is simply no economically viable machine that can cope with.

[Padishar]

Basically, yes, the CPU is far more important than the graphics, any reasonable spec graphics is capable of running quite high part counts at decent frame rates though some older integrated chipsets do struggle unless you turn the settings down. There are lots of areas of the game that use a considerable amount of CPU: Unity's rigid body calculations, collision detection, heating mechanism, aerodynamics, resource production and consumption, docking port/claw handling etc. Several of these operations effectively scale with the square (or even worse) of the part count so as the part counts get larger, these calculations take up proportionately more time and start affecting the frame rate.

There seems to be a general consensus that the game has gotten slower in recent updates, the same large craft being substantially slower in 1.0+ than they were in 0.90. This isn't really surprising given the new heat mechanics and aero changes.

The Unity 5 update coming in KSP 1.1 should improve the rigid body calculations and there is lots of scope for parts of KSP to be optimised also. Hopefully things should improve again in the coming months (and possibly get significantly better than they've ever been).

6 gig of memory should be fine unless you like running other memory hungry programs while you play (e.g. browsers, mod development software etc.). Any more than that is wasted really as the game simply can not use more than 3.5 gig (assuming running on 64 bit windows, if on 64 bit Linux then it can use more).

The best CPU for KSP at present is the fastest clocked recent Intel CPU that you can get. Don't get less than 4 cores unless on a really tight budget (there is a very cheap Pentium branded chip that can be overclocked very well which isn't a bad option) but hyperthreading (2 logical cores per physical core as in most i7s) isn't particularly helpful (certainly not now and probably not for the foreseeable future unless you also do stuff like video transcoding).

[Jaeleth]

Thanks for your insight and advice, Padishar.

[cantab]

Also, 1200 parts will lag on any processor.

[Wild Cobra]

The best CPU for KSP at present is the fastest clocked recent Intel CPU that you can get. Don't get less than 4 cores unless on a really tight budget (there is a very cheap Pentium branded chip that can be overclocked very well which isn't a bad option) but hyperthreading (2 logical cores per physical core as in most i7s) isn't particularly helpful (certainly not now and probably not for the foreseeable future unless you also do stuff like video transcoding).

Disable hyperthreading in the BIOS if your CPU has more logical cores than physical cores. It will approximately double your framerate.

[Padishar]

Disable hyperthreading in the BIOS if your CPU has more logical cores than physical cores. It will approximately double your framerate.

Several people have claimed this but, from the testing I have done (on both a 3770 and 4770K I see no measurable difference when turning off HT), it is simply not true. It is more likely that when HT is enabled your CPU is deciding to throttle down because it doesn't think it is being used enough to justify a high clock speed. With HT off, the apparent CPU usage will be double and it is less likely to throttle down.

[cantab]

Chances are it varies depending on setup. Regardless, it doesn't hurt to try it.

[Jansn]

Disable hyperthreading in the BIOS if your CPU has more logical cores than physical cores. It will approximately double your framerate.

it is simply not true.

But i also can confirm that disabling HT on my 4790K helped a lot to make KSP run smoother a lot.

I use many wellness-, sound- and visual plusins, part plugin just the Tantares LV/SCANsat/Station Science..

I play on Linux/Lubuntu 14.10, now 15.04. (with Intels microcode-kernel-patch.)

I had many stuttering and this short breaks each 1-2 seconds, even at low part-count vessels.

Since i disabled HT it runs extremely smoother.

I also still have a long-term-extra-boated-all-insavegame in an extra installation, quite dead, dont play it anymore

but sometimes i look into by curiosity, and there is exactly same behavior, just in an more extreme condition.

(250 mods!)

Dont know and i am not interested in whats true or not, its just my own experience.

Edited October 21, 2015 by Jansn