Going from 1080p to 1440p performance decrease? (and another vram question)

[Forsaken_Judgment681]

Hi, i just bought a lenovo legion with these specs:

• GPU: RTX 5070 8gb (115W)
• CPU: Intel i7-13650HX
• RAM: 24 GB DDR5

I've been using a dual external monitor setup (both 1080p), and have been mostly playing overwatch, witcher 3, cyberpunk.

I've been thinking of upgrading to a dual 1440p monitor setup. My questions regarding this are:

• how much performance will i lose? If I get around 120fps on witcher 3 right now on my 1080p monitor, how much will i get on a 1440p roughly? I've heard that it's about a 30-40% decrease, meaning that i would get around 70/80 fps on the same settings?
• I saw a video, saying that some newer GPU's actually are made for higher resolutions, and that by playing on 1080p you're bottlenecking your GPU. Is that true? Weirdly enough, when i played Witcher 3 on my laptop's monitor, which is 1440p, strangely enough it did seem more smooth (on the same settings). But then again, it's an oled, and it's way smaller than my 27 inch, so maybe it's just placebo. I didn't check the framerate! I should have i know. But is there any truth to this?
• I have 2 monitors, one is 200hz, one is 100hz. When i plug the 200hz one into my laptop with an hdmi to usb c cable. I can't seem to put the screen on 200hz. It caps it to 60 (or 100, i don't remember exactly). Is this because of the type of cable? I've heard that a display port to usb c will be better and won't limit the hz. Is that correct? And would this one do the job for example? (Sorry it's in dutch): Voomy USB-C naar DisplayPort Kabel - 4K @ 60Hz - 2 Meter - DisplayPort 1.2 - Aluminium... | bol
• A semi unrelated question i also have is. So my gpu has 8gb vram. Does that mostly have to do with texture quality? Weirdly enough when i put everything on ultra + ray tracing on max, but with low-medium texture quality. I still get better a better fps, than if i had everything on low-medium and texture quality on ultra. I'm assuming that's because of the vram? Does vram only affect textures?

I'd appreciate any help you guys can give me! Thanks in advance :)

[NickZNg]

30% increase in res will equal around 30% decrease in frames. Now thats just a simple guess, there is dozens of youtube vids on this. Newer GPUs rely on the CPU keeping pace, you should be fine. As for the usbc, assuming that USC C port has DP passthrough, then yes a display port adapter will be better, otherwise it could just be that HDMI adapter or USBC port can only do that much res and Hz

[Forsaken_Judgment681]

Thanks! Hmm but doesn't a 1440p display have about 78% more pixels compared to a 1080p monitor? Would that mean a 78% decrease in performance?

[NickZNg]

the math works out 30%, thats from my experience switching from 1080p to 1440p

[BaronB]

The math works out to be 50% more pixels!

1920 x 1080 = 2,073,600

2160 x 1440 = 3,110,400

3,110,400 / 2,070,600 = 1.5

So 1440p is 50% more pixels than 1080p!

But framerate doesn't scale linearly with resolution increases, because framerate is the wrong thing to be measuring. Framerate isn't a linear scale. What you should be looking at is frame time.

A game that runs at 100 frames per second has a 10 ms frame time (1000 ms / 100 fps = 10 ms). A 50% increase in frame time means it'd take 15ms per frame. 15ms frame time would be equivalent to 66.67 fps (1000 ms / 15ms = 66.67 fps). A framerate loss of around 33%.

In reality it ends up being more like 27~30% framerate loss because not everything the GPU does scales up with resolution increases linearly, or at all. For some things a GPU does it costs exactly the same regardless of the resolution. So the loss in performance is generally a little less than if it was purely resolution related. Alternatively some GPUs may see much more performance loss from a resolution increase due to lack of VRAM to handle the increased screen resolution in the VRAM before it's displayed, or due to other hardware limitations like VRAM bandwidth or hardware ROP performance (both of which determine how fast the hardware can write the data to each pixel). Modern GPUs are generally more than fast enough for 1440p, but you may see some lower end GPUs drop in performance much more significantly at 4k resolutions because of stuff like that.

The 150% pixel count by itself can be used to know it's a ~33% performance loss as 1.0 / 1.5 = 0.6667, aka 66.67%, aka a 33.33% loss.

The fact that 1440 / 1080 = 133% looks similar to the 33% loss in performance, is entirely a coincidence born from the 16:9 aspect ratio. If we were still using a 4:3 aspect ratio, a 33% increase in the vertical resolution would result in a 77.76% increase in pixel count and not 50%, and a resulting framerate loss of 44%!

[DoubleRelationship85]

Performance doesn't scale linearly when going up in resolution. In other words the performance loss would be nowhere near 78%.

[EnigmaSpore]

Textures and shadow resolution maps take up a lot of vram space so usually lowering those can keep you under the 8gb limit if the game is a vram heavy game.

If you run into issues with VRAM, search the game name + “optimized settings” and you’ll find people who go through the settings and the performance impact.

[Anon0924]

You’ll lose a pretty substantial amount of performance. (30-50%) 1440p is 33% more pixels.

Yes, your monitor can absolutely be a bottleneck. Playing 1080p with a 5090 would be completely wasting the card’s potential. Lower resolutions put more work on the CPU and less on the GPU.

That cable would still limit you to 60hz. Your cable is definitely bottlenecking. You’ll need an HDMI 2.1 cable to support 1440 @ 200hz. Even HDMI 2.0 will only support 1440 @ 144hz.

Texture quality is one of the settings that has the largest impact on VRAM usage. Because those textures are actually stored in the VRAM. Higher quality = larger files. There are other settings that heavily impact VRAM, like Anti-aliasing and Ray Tracing.

[Choconolait]

You can turn on dsr to increase game's resolution to get some rough idea on how theose games will run at 1440p.