RTX 3080 vs 6900 XT benchmarks and my decision

[carlito777 712]

Dear all,

since I’m facing the decision whether to keep a RTX 3080 Founders Edition or an AMD RX 6900 XT and all the “evidence” on the Internet is quite inconclusive, I did some testing of the cards on my own. In the following, I will illustrate some of my findings as this might be interesting to some people which are facing a similar decision.

Test system:

i7-10700K@5.0GHz

32GB DDR4-3600 RAM

OS and MSFS on SSDs

Scenarios:

In order to compare apples to apples, I tried to use scenarios which I could easily replicate and were not subject to unwanted variation. So for all the testing, I set the date to Jan, 15^th of this year and the time to 12 noon. I used the Ultra preset in all scenarios and I’m running the sim in 4K. I also turned off all air traffic (so no AI or real time traffic). All fps and VRAM figures are from inside the cockpit. So no outside shots!

I chose scenarios where I would start at the runway of a large airport (exception Courchevel and Yosemite) facing the direction of a large city and I picked the runway so that the airport buildings were in sight. All the numbers for “on runway” were recorded while sitting on the runway, ready to take off. I waited a couple of seconds before recording the numbers to let the system shake off a bit. Then I took off and maintained runway heading and leveled off at 2500-3000 feet at a speed of roughly 250 knots. That way, I flew across the city to record the “Over city” numbers. The average fps were measured from take-off until I crossed the city. In the case of KLAS, which I used as a VRAM worst case, I had to make a sharp turn to the right after take-off to fly over the city (of course ;-)).

The KJFK, EGLL, KLAS and Sydney landing challenge scenarios were all flown in the stock A320. Courchevel in the TBM and Yosemite in the C172 G1000. The Yosemite scenario used an older version of the Yosemite Valley add-on from VFXSimmer and I started the scenario airborne at Half Dome and flew around Half Dome.

Both graphics cards were at stock performance. No overclocking. The VRAM is usage from the dev OSD in MSFS. So this represents usage not just allocation.

So here are the results:

6900 XT:

RTX 3080:

My key findings:

1. The cards perform roughly the same in 4K. I really do not understand how some Youtubers and other testers on the net find that the 3080 outperforms the 6900 XT. This is just not the case. Apart from the scenarios shown here, I tested a lot of other scenarios and the 6900 XT never performed worse than the 3080.

2. Even though the 6900 XT often uses more than 10GB of VRAM, the 3080 somehow manages to use less without performance suffering a lot. Why am I saying “a lot”? Because my very subjective impression is that the 6900 XT performs way smoother with much more even frame times. Most likely this is because it can use more VRAM.

3. Another very subjective finding is that the 6900 XT has much sharper textures in the far distance, e.g. in mountainous terrain. Could also be, because it can load more textures into its VRAM.

4. In the Yosemite scenario, which is also heavy on VRAM, the 3080 really struggled. The performance was choppy and some textures didn’t load at all. So Half Dome looked way better on the 6900 XT.

What’s my conclusion?

The 3080 can handle MSFS 2020 in 4K well. However, the 10 GB VRAM is a limitation. Not to the extent that performance tanks, but it has an impact on frame time variability and maybe also texture sharpness. Given that MSFS 2020 is going to move to DX12, I would assume that 10GBs will be even more of a problem. This is not saying that you are not able to enjoy MSFS in 4K on a 3080. It’s just that more VRAM improves the experience.

The 6900 XT performs excellently in MSFS2020. The performance is always smooth and the card really seems to be up to the task at all times. Together with the fact that XBox also is based on RDNA2, I speculate that AMD graphics cards will benefit from the move to DX12 and the optimizations that are coming to MSFS 2020 in the summer. All this is the reason why I’m going to keep the 6900 XT and sell the RTX 3080.

Best regards

 

[Space Monkey 24]

Thanks for sharing you findings, I was mulling over my options when we're back to normal availability. 

I've seen some comments/concerns  about AMD and lack DLss which I think is about scaling to your resolution. Is this feature a concern when playing at 4k resolution on AMD cards.

 

Regards

[carlito777 712]

AMD is developing Fidelity FX Super Resolution together with Microsoft. I bet, this will make it to MSFS because most likely it is required to get 60 fps on 4K on XBox. I really don‘t think DLSS will ever make it to MSFS. It‘s of course a different story with other games. 

[TrentXWB 20]

8 hours ago, carlito777 said:

What’s my conclusion?

The 3080 can handle MSFS 2020 in 4K well. However, the 10 GB VRAM is a limitation. Not to the extent that performance tanks, but it has an impact on frame time variability and maybe also texture sharpness. Given that MSFS 2020 is going to move to DX12, I would assume that 10GBs will be even more of a problem. This is not saying that you are not able to enjoy MSFS in 4K on a 3080. It’s just that more VRAM improves the experience.

The 6900 XT performs excellently in MSFS2020. The performance is always smooth and the card really seems to be up to the task at all times. Together with the fact that XBox also is based on RDNA2, I speculate that AMD graphics cards will benefit from the move to DX12 and the optimizations that are coming to MSFS 2020 in the summer. All this is the reason why I’m going to keep the 6900 XT and sell the RTX 3080.

Best regards

Thanks for this! Are you planning to do the same comparison with P3Dv5?

[Ted Striker 338]

Very well done comparison Carlito. Thanks for taking the time to post your test results and conclusion. I would also be interested in the same comparison with P3Dv5 if you use that sim.

Ted

[carlito777 712]

Thanks, Ted. You are very welcome. Unfortunately, I don‘t have P3Dv5. I went from P3Dv4.5 straight to MSFS. I rarely use anything else these days. (And I already sold the 3080 FE right after the tests. Took me less than 30 minutes to sell it. ;-)) Of course, it would be interesting to see how both cards perform in P3Dv5 since P3Dv5 is already DX12. 

[Sunshine13 234]

Carlito 777even though I have a 3080 and not yet on flight simulator 2020, your study is very detailed, and I commend u for the work that it entailed. When I get onto flight simulator 2020 in the next couple of months, probably will stay with my 3080., and thats just me.

By the way, when some one like yourself performs a study comparing those 2 video cards, and was completely objective, this is what makes Avsim, such a great forum to exchange and debate different issues, and ideas.  HELPS us all!  +1

[Flyfaster_MTN002 412]

Why is there no mention about the monitor that was used and if it had G-sync etc. ?  Seems that is a big factor!?