Effects of the iFPSClamp setting on New Vegas

[Werne]

I've written this a few days back but I got busy in the meantime, taking care of a baby is a lot of work. But I got around to finishing it up now, so here it is. :smile:

 

A few months back I managed to solve one of the things that bothered me to no end in New Vegas yesterday - the stuttering. But after a while I discovered the solution was not as great as I though, it was still effective once tweaked correctly though. I also figured out something awesome along the way, which I will show you. And you guessed it, it's all connected to the iFPSClamp setting in FalloutPrefs.ini and Fallout.ini.

 

Anyway, the game has been a big stuttering clusterf*** since day-one for me, even at stable 60FPS the game was stuttering like crazy, and I tried to solve it with stutter remover - no go. Then I thought was caused by a weak graphics card (got a Radeon 7770) so I dropped the framerate to 45FPS to make it stable, which only made the stutter worse. Dropping it to 30FPS made the stuttering so bad I had a feeling i was looking at a slideshow even though the framerate was there. Uncapped it again, stable 60FPS with a 115% chance of stutter.

 

So I started playing with the inis, done a whole lot of changes which did nothing, even dropped the game to it's lowest possible settings and that also did nothing, it was still stuttering away like mad. But then I tried the iFPSClamp setting, I let the game run at 60FPS and used iFPSClamp=60 in both FalloutPrefs.ini and Fallout.ini. That one worked great, the stutter was completely gone and the game was butter smooth.

 

 

 

However, if you think that's the right way to do it, you're dead wrong. You see, I didn't know what the iFPSClamp setting was exactly, but I used it anyway, which was not that great of an idea without educating myself first.

 

On first glace it looks like a setting that allows you to set the FPS, it makes the game smooth at the refresh rate set there so it must be it, right? Wrong, it seems that iFPSClamp seems to control the engine's sync with the render thread, setting it to the exact refresh rate of the monitor seems to sync the two. On one hand, that is a good thing, but on the other hand, it is a very bad thing. iFPSClamp can be your best friend or your worst enemy, depending on how you use it.

 

For me it was a nightmare. Unknowingly, I've messed up a lot of things, and it took weeks of troubleshooting to get what's going on. First up was this little problem...

Well, maybe I should have listen to Easy Pete when he warned me about dynamite. And if you think that's bad...

 

... imagine having ET as your character's parent. When I moved around the fingers kept shrinking back to normal size and growing to that size again, sometimes they'd even get smaller. Damn creepy if you ask me.

 

But wait, there's more!

And here I thought Deathclaws are scary. :blink:

 

Anyhow, a deformed character is the least of your concerns - scripts go to hell, havok goes to hell, rigging goes to hell, your saves go to hell, EVERYTHING GOES TO HELL. It took me weeks to figure it out, since the problems were happening with my character at first, I assumed there was a problem with the skeleton or animations, but it wasn't. Other problems started manifesting themselves so I did other things to try and stop them, nothing worked I did everything I could but got nowhere... until I set iFPSClamp back to 0. Lo and behold, the problems stopped immediately, like nothing ever happened.

 

Then I tried playing around with it, setting it high, setting it low, trying it to see where it takes me. And that's when I found the awesome - you can change the game's speed by adjusting the iFPSClamp. For example, this is what happens when you set it too low:

https://www.youtube.com/watch?v=wiNaQkGIJww

Remember kids - say no to skooma, or you'll turn into a human equivalent of Speedy Gonzales. :wink: If you're too young to know who Speedy Gonzales is, Google is your friend.

 

The effect is awesome, the game is 3x faster in that video (iFPSClamp of 15 at 45FPS fixed during recording = 3x slower), just imagine a Deathclaw at that game speed. :ohdear: And this one is interesting, it seems that setting it lower than your stable framerate still makes the game smooth (I use 59, been running smooth as butter for months), but doesn't introduce the problems shown in the pics. So what happens when you set iFPSClamp too high? Exactly the opposite of setting it too low:

https://www.youtube.com/watch?v=lKfk6R7yI6o

Slow motion! :woot:

 

If you ever wanted to see just how crappy animations are in New Vegas, set the iFPSClamp sky high and do your thing. It's a nice effect though, if it's possible to temporarily manipulate ini settings in GECK you can use something like this through scripted events to create slow motion on demand. Funny enough, setting iFPSClamp too high also doesn't affect the game in a way shown in the pic, only setting it to the capped framerate you play at makes it go to hell.

 

 

However, there is something problematic when playing with iFPSClamp. You see, my framerate is constant, I never saw New Vegas going under 60FPS, which is why I can tweak the setting to suit my needs. But if the game were to dip under 60FPS, I'd get slowdowns. It doesn't continue at the same speed, once you go under the iFPSClamp setting, the game begins slowing down, how slow depends on your framerate as demonstrated in the second video. I'm not sure what kind of an effect would that have on the game cause I didn't try, would it run well or would it exhibit issues like in my pics - I got no idea.

 

 

 

So to put all this simple, don't play with iFPSClamp unless you know precisely what it does and what are the consequences of tweaking it. As you can see in the three screenshots I provided, the side-effects of doing it wrong are not pretty or easy to troubleshoot later on. But if the game runs at 60FPS stable and stutters, setting it to something like 59 should be fine, though it's a hit-and-miss setting so 59 may not be the best, you could still end up looking like a human/Deathclaw hybrid.

 

And just in case you're wondering, yup, this works in both Fallout 3 and New Vegas, also Oblivion, not sure about Skyrim though.

 

Well, that's all I got for you. If your game explodes when playing with this setting, you get to keep the pieces. Can't say I didn't warn you. :D

Edited April 6, 2014 by Werne

[JimboUK]

Ha, I learned a long time ago to leave that alone, I had the same problems as you.

[tjmmilldog]

So what does changing it to 1 or 0 actually do to the game-play; as some guides say to do?

[JimboUK]

So what does changing it to 1 or 0 actually do to the game-play; as some guides say to do?

 

I think a setting of 0 ties the physics to the framerate, anything else tends make really odd things happen so changing it isn't recommended.

[NeoandGeo]

When using iFPSClamp it's recommended to strictly use Clamp=60 and 60hz on your monitor. Haven't had any weirdness using it like this with 100's of hours in FO:NV/Skyrim/FO4. The two videos perfectly illustrate what happens when the command is misused.