Video RAM requirements for KSP

[Kerbin Dallas Multipass]

I think you and your system will be perfectly happy if you spend ~100 bucks on a new video card;)

Edited January 25, 2015 by Kerbin Dallas Multipass
wanted to say about 100 bucks plus minus 20 bucks

[J.Random]

VRAM doesn't matter much...

Until you switch to -force-opengl, install a ton of 4K-8K planets/clouds textures and convert all textures to dds. Then at some point you may get occasional fps drop (sometimes to the point when you have to call it SPF instead of FPS) and this kind of error in system logs: "The NVIDIA OpenGL driver has encountered an out of memory error. This application might behave inconsistently and fail."

[_Aramchek_]

VRAM matters more than you think, especially since the op wants to go 4k.

I understand it's more initial cost, but I've been doing this for years and years and you will save money in the long run going to something that has at least 3-4gb's minimum for that resolution.

[Redchrome]

I did some experimentation on my Linux box, and found a few things:

* The box has graphics built into the mobo. It's the crappy kind where the GPU 'steals' RAM at boot time for video use. The BIOS allowed me to experiment with different amounts of VRAM allocated.

* With 64MB VRAM, KSP was remarkably playable. Running a FurMark test got a whopping 5 FPS but that test is a lot harder than KSP. It's the same performance I get on my iMac with 256MB VRAM (but a crappier processor).

* Even with relatively tiny amounts of VRAM, I could still load much nicer textures on the Linux box compared to the Mac. Maybe this is because the built-in GPU is hitting RAM no matter what, so it doesn't matter how small the VRAM is.

* In some ways I actually got worse performance when allocating more VRAM - the CPU spent more time in a wait state when using 1GB VRAM (about 80%) when compared to 64MB VRAM (about 60%). I haven't looked at the debug console to see if I could tell any difference in render rate.

* I found while watching 'top' that the CPU was spending most of its time in a 'wait' state. Definitely wasn't waiting on disk or networking tho (disk activity measured with dstat).

* Digging through old computer parts I found what turned out to be a 10-year-old Radeon X700 with 256MB VRAM. Ubuntu 14.04 automagically sets up the drivers and DRI for it (which still shocks me considering how much trouble that was years ago). FurMark performance is truly atrocious and the driver doesn't even render the test image correctly, but the CPU is barely working and isn't waiting on anything, so the wait times on the built-in graphics must be for data transfers through the CPU from the GPU to RAM (ow!).

So yep, a nice shiny new graphics card should give a nice experience. Now if only I can decide on a monitor...

[Nobody_1707]

With all the fancy textures KSP uses for models tho, I find myself needing to run 1/8th-res textures in order to get decent performance. I've got an OSX 10.10.1 box with 12GB RAM but only 256MB VRAM. I just found out that the OSX version is only 32-bit, so that's pushing me to switch over to my Linux box (and 64-bit KSP), which has a faster CPU. I'll want more RAM for it tho, and probably an upgraded video card.

OS X 10.10.1 is very definitely 64-bits. I believe 10.7 was the last version that supported 32-bit processors. Not that it matters much, since you're building a new computer anyway. But Macs have been 64-bit since 10.6*.

*Actually, it's supported 64-bit programs since 1.5, but the UI library didn't have 64-bit support until 10.6.

Edited February 5, 2015 by Nobody_1707

[steve_v]

OS X 10.10.1 is very definitely 64-bits. I believe 10.7 was the last version that supported 32-bit processors. Not that it matters much, since you're building a new computer anyway. But Macs have been 64-bit since 10.6*.

Ja, but there's no 64bit unity for OSX, therefore 64bit OSX is irrelevant for KSP. The elephant in the room is still the 32bit address space limit, since all textures are loaded into system RAM before VRAM even comes into the equation. As long as you have sufficient VRAM for the textures actually used in the most complex scene, plus some for shaders / AA etc. it'll run (but perfomance will suffer for all the texture swapping). I'm not sure what the true minimum is for KSP, but I'd be surprised if it's >128MB.

Of course if you have a machine that can run OSX, it can also run GNU/Linux, so there's no real need for a separate box

Edited February 5, 2015 by steve_v

[NecroBones]

Thanks Slugy,

I don't know what good performance is, especially not for things like KSP. Some cursory looking over various articles shows that for games which don't work the graphics card so hard (which is KSP from what people are telling me), having a high-end card doesn't make so much of a difference. This is good, because it means I can optimize for things like quiet operation rather than memory size or rendering speed.

I'm still pretty sure I want 2GB of VRAM, for the sake of being able to drive a 4K monitor and have some degree of future-proofing.

For the same reason I'll get an extra 16GB RAM, because it's cheap and I've never regretted buying twice as much RAM as I thought I needed.

I'm still enough of an old Linux geek to mistrust closed-source drivers. I'll have to compare how well the nVidia open-source vs. closed-source drivers work. It's obvious that the closed drivers work better, but how much that matters for KSP remains to be seen.

What do people use for figuring their frame rates in KSP?

- - - Updated - - -

Already got the quad-core i5 (from /proc/cpuinfo: Intel® Core i5-3570K CPU @ 3.40GHz ); just need better graphics and a bigger monitor.

Awesome.

I know I'm chiming in late, but I thought I'd throw in an additional point of reference.

I'm using windows, but with a Core i7 4770k @4GHz, 16 GB RAM, and NVidia 760GTX. KSP runs great. Of course it'll still lag with high part-counts, but that's unavoidable.

But the reason I wanted to mention this, is that you'll really enjoy having 16 GB of memory. It's enough that I can run KSP, Photoshop, Blender, and Unity all at once (while modding), as well as Firefox with about 20 tabs open, and I don't thrash. The memory is worth it.

[Redchrome]

I got an ASUS nVidia GTX 750 Ti Strix vid card with 2GB VRAM. Had some troubles getting the system to boot with it at first (seems to have been a BIOS bug that somehow requires two monitors to be plugged in, at least the first time the hardware is booted -- weird). Installing the drivers was easy. Getting them to work required some fairly extensive Linux admin knowledge and googling. Now that I have them working tho...

WOW! So this is what KSP is supposed to feel like! I never realized how much it sucked to have physics rendering everything at half speed.

As a point of reference, the base game - no mods - running at 1600x1200 with the texture resolution turned all the way up takes about 1.5GB of VRAM (as reported by nvidia-smi).

Once my 4k monitor arrives next week I'll get to see how well that works.

[Redchrome]

With the 4K monitor, and my heavily modded game (no texture compression or other RAM-reduction mods tho), I'm quite surprised to see nvidia-smi reporting VRAM usage at only about 1200MB. So it seems the VRAM requirements aren't *that* onerous and 2GB VRAM works just fine.