CPU vs GPU Limit

Curious about difference in MSFS2020 behavior with a CPU limit vs GPU limit?

For example, would be curious how a new Alder Lake 12900K system with a 3080 or even a 3070 TI GPU would perform the sim vs. something like a 11700K or even a 10700K with a 3090.

For right now the sim is mostly CPU limited when framerates count the most (Dense built up areas and airports/ Approach)

It usually becomes GPU limited when you are not in those scenarios (cruise levels in flight). Performance would be best served with more CPU power up to the point where the Sim has no problems feeding the GPU frames in those dense environments such as built up addon airports and complex AC.

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In VR it is strictly GPU limited even with an 3090.
In pancake vision it is CPU limited mostly but of course you can drive the settings to make an 3080 sweat and burn an 3070/ti

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Settings would be maxed/Ultra across the board, except no live traffic and possibly no lens bloom. Debating between 1440p or 4k pancake mode. Target is a smooth, playable framerate with 40fps minimum, ideally 60 fps.

Most likely will get Alder Lake 12700 or 12900 with liquid cooling. Can I get away with a 3080?

Short answer yes… Not happy with the Vram on the standard RTX 3080 (for future proofing when serious airport addons and traffic come into play) but That’s good enough for 1440p or ultrawide 1440p. Not sure about 60fps at 4k though in dense urban areas though… that’s a big ask.
I would focus on the cpu (Alder lake probably) and start out with a RTX 3080ti for now… that should run whatever you throw at it presently. As the sim gets more complex then you will have to re assess as time goes on.

That’s not entirely accurate. The CPU vs GPU limiting factor is highly dependent on resolution. Typically at 4K or higher, you’ll be GPU limited with some exceptions.

You won’t be able to get 60 fps at 4K on Ultra with current-gen cards, but getting at least 40 fps should be easily achievable. If getting 60 fps is important, I’d suggest considering 1440p.

As both of many have replied … there’s just so many options to do so many things with hardware and to some extent software.

I take a 3060 12gb into a small dark room and beat it mercilessly while my notoriously hot heated 9900k laughs cool and stoic @ 5ghz … three 1080monitors with nV surround, all ultra, bumped up 5760x1080 to 6400x1200 and LOD’s @ 5X

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So 3090/3080ti still cannot get 60fps on 4k, even with i9 Alder Lake 12900 and optimized Windows 11?

40fps would be easily achievable in 4K Ultra on which GPU(s)? I can get a 3080. Can possibly stretch to a 3080ti, but the 3090 is a bit steep at the moment, unless it is leaps and bounds better than the others.

I’ll plan to get either a 12700 or 12900 depending on the price/performance for either option.

I currently have a non-gaming but still decent quality 4K 27" 60hz monitor with freesync that apparently adaptive sync only works for 40-60hz, hence the 40fps minimum in 4K Ultra.

However, it is MUCH cheaper to not get a 3090 and get a lesser GPU (3080) and a separate modern gaming specific 1440p G-Sync monitor and run in 1440p Ultra.

Its mostly accurate. Im not going to take the time to explain the exceptions of VR or people (like myself) who like to run the sim above render scale 100 to push the GPU…
I consider those edge case and not the normal population

Its not that i dont know the edge cases but my comments cover most use case non VR scenarios. VR users can chime in as they did in the thread thank you.

  1. We dont have alder lake chips yet
  2. We dont yet have a scenario (To my knowledge) where we are flying into KJFK / KORD with full traffic at 4k ultra and not have the sim flip to limited by mainthread to really see where we are in terms of how limited we truly are by the best GPU on the market.

So everything Alder Lake is speculation … Looks promising…no doubt and i would wait for it but speculation until the sim benches come out.

My specs
5900x /Manual PBO with the CPU tuned to hit 5ghz effective clock in burst but 4.95 sustained
6800xt Red Devil / OC by default …
32Gigs ram Cas 16 with timings manually tightened
Sim Render Scale 110% / Stock Ultra Settings / 65% Traffic
On a 3440x1440p Ultrawide with Vsync unlocked i sit around 58 to 60 fps for 90% of my flight in the A320NX… I however have started to lock Vsync to an effective lock of 50 fps. As stated before… The sim will flip to CPU limited somewhere on final and drag the frames down to the thirties and forties.

Again i would recommend the best Alder Lake Cpu you can get (After really going through the reviews… no day one purchase just to make sure.) and Match it with a 3080ti…
Keep your stock Ultra as your non negotiable and adjust resolution or render scale to get the desired frame rate target you want to achieve.

Hope this helps…

I can’t comment on performance with Alder Lake, but my setup with a Ryzen 5950x and 3090 can’t hit a stable 60 fps on Ultra at 4K.

If you plan to game at 4K, I wouldn’t dwell too much on processor choice and spend more on considering a higher-end GPU. As mentioned in my previous post, you will likely be bottlenecked at the GPU at 4K resolutions. In other words, your GPU becomes the controlling factor on performance at 4K resolutions. However, I wouldn’t recommend the 3090 unless you have uses for the high VRAM. The performance difference between the 3090 and 3080 is minimal (10-15%), and not worth the double MSRP price tag. You would be better suited to use that money for other, more impactful components.

In 2021, I would hardly consider 4K gaming as “edge cases” as it becomes more mainstream. I’m simply pointing out that resolution is the biggest controlling factor in CPU vs GPU bottlenecking. If people are planning to use 4K, they should know their processor choice becomes less relevant.

Likely and Is are two different states. Again … im not talking about VR and you seem to be putting all your focus on 4k … Not everyone here is trying to run 4k or can run 4k … If you are running 4k or VR YOU DO fall into the Edge case.

My observations still stands …
OP can decide where he wants to go with the advice given


At some point you simply move the bottleneck elsewhere and with a game that streams pretty much all the scenery that point gets reached pretty quickly.

I’m looking forward to 2 major upgrades in the coming months.

  1. Alder Lake (and maybe ddr5, will wait to see performance, prices and what motherboards are available.)

  2. Gigabit fiber. :slight_smile:


It’s hard to be certain of the perfect set up but I think if your GPU stays around 95 - 98% usage over mixed terrain and your CPU never gets stretched you’ll be alright. Of course that you must regulate with your settings and conditions change so it’s hardly a magic formular, it’s whatever works best for you I suppose. I haven’t yet found the need since getting my new card but with the old GT1030 any sign of a city and it had me scurrying to options to lower my settings.

I agree Alder Lake looks promising thus far and Gigabit is a must for those who can.

Something I rarely see mentioned is Intel Arc Alchemist graphics card.
I missed the MSRP bandwagon on the 30 series, and the high end Intel card is squarely in my crosshair.
Price/performance wise it looks promising, also curious how it will play with the new Intel chips.

I managed to pick up a 3090 at regular retail price early 2021.
Was really aiming for a 3080ti but it wasn’t released at the time and luckily nobody wanted the 3090’s so they were easier to order than the vanilla 3080!

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I had to buy a power supply that has a 15% chance of catching fire if I overload it to get mine :crazy_face:

Oh one of those. I hear that they make good toasters…

What do you mean?