Down scaling and it's effects or lack there of on system performance?

[Sabercbr929]

I'm sorry if it's already been covered I'm a first-time poster and if it has please let me know, but I'd be interested to see how down scaling a higher resolution monitor to lower resolution effects system performance.  I've read on some forums or publications that suggest, with no definitive testing, that it could potentially tax the gpu up to 4x as much when compared to running native resolution in either 16:9 or 21:9.  The explanation on the down scaling from higher to lower resolution suggest that even though the resolution may be lower the pixel density of say a 4k monitor at 32 inches running 1920x1080 demands greater gpu horsepower to drive the more densely populated screen.  I know it's true that with DLSS 2.0 the effects of up sampling can improve in game fps due to the gpu rendering at lower resolution, so to me at least it wouldn't make sense that down scaling would have any negative impact on the gpu.  What are your thoughts? 

[Chris Pratt]

Downscaling means you're rendering at a higher resolution than what can be displayed. So, if you've got a 1080p display, but you're rendering at 1440p and downscaling to 1080p, the card is having to render 2x as many pixels as native, and thus will be half as powerful (i.e. FPS effectively will be cut in half). This can be an effective alternative to other AA techniques if you've got the horsepower to spare, but if you're already using your card to the max, it's just going to be a worse experience.

[Enderman]

If you're talking about supersampling, that is where you run the game at 1440p or 4k on a 1080p monitor, and it 'downscales' the image to fit. This means you get a sharper image but it takesmore GPU power to run, since you're basically playing the game at 1440p or 4k instead of 1080p.

 

If you're talking about changing your monitor resolution to something lower, like having a 4k monitor but setting your PC to output 1080p (and the monitor upscales it to fit 4k) then essentially you're playing the game at 1080p so your performance is much higher but the details are all worse.

[SkilledRebuilds]

Or... is he talking Desktop Overheads by using Nvidia DSR 4X....?
1080p Desktop with DSR active for 4K Games...

VS 2160P DSR Desktop (Zero filtering in DSR) and playing in 4K DSR...

I have DSR activated with Zero filtering set for 4K specifically, and my desktop runs at 2160p (faked) and so do my games.
Only when using non 1:1 scaling (1440p) do I then use DSRfiltering again...

So the overheads of Desktop would increase and be more demanding is the question asked?
Answer is yes, but how much I cannot say (outside of VRAM usage)

[Sabercbr929]

I believe Enderman's second statement best describes my situation, having to upscale a game running at 1080p  to fit a 4k monitor in this explanation is upscaling not downscaling my mistake.  So in the situation where up scaling a game from 1080p to fit a 4k monitor, isn't the gpu still driving the same amount of pixels as if it were running the game in 4k?  @ Skilledrebuilds that's an interesting statement I appreciate your input!  @ Chris thanks for the clarification.

[Chris Pratt]

1 minute ago, Sabercbr929 said:

I believe Enderman's second statement best describes my situation, having to upscale a game running at 1080p  to fit a 4k monitor in this explanation is upscaling not downscaling my mistake.  So in the situation where up scaling a game from 1080p to fit a 4k monitor, isn't the gpu still driving the same amount of pixels as if it were running the game in 4k?  @ Skilledrebuilds that's an interesting statement I appreciate your input!  @ Chris thanks for the clarification.

No. The render resolution is the render resolution. Upscaling alone doesn't require anything. Now, things like DLSS use AI and lean on the tensor cores of the Nvidia GPU to upscale in a smarter way than just making 1 pixel into 4. That takes some amount of processing power, but it's pretty minute overall.

[Sabercbr929]

1 minute ago, Chris Pratt said:

No. The render resolution is the render resolution. Upscaling alone doesn't require anything. Now, things like DLSS use AI and lean on the tensor cores of the Nvidia GPU to upscale in a smarter way than just making 1 pixel into 4. That takes some amount of processing power, but it's pretty minute overall.

Makes sense thank you for the comments!