Very true. I use an old 2600K gaming desktop in a very large case and it's my main NAS for all my important backups.

However, the OP stated: "However, getting back into MSFS 2020 again, it's starting to cause some lagging in the graphics department. "

MSFS requires a lot of resources and I am afraid that upgrading the video card from gtx1080 SLI to let's say an RTX 3080 is not going to work well, and they would be better served with a newer system. That's just my opinion.

I absolutely agree with you for OP's specific circumstances. I thought we segued to a general discussion about restoring/upgrading classic rigs.

MSFS recommended “ideal” system is i7-9800x + rtx 2080.  If OP has R5, then there is a path to meet such requirements.

i7-9800x is standard cpu supported by R5.

Understood. I think Vanadiel's point is that if OP has to purchase a new CPU and a new graphics card to upgrade their R5, then that $$$ would be better spent going towards a new modern computer. When I modded my R5 it was more of a fun project and the nostalgia of owning an Alienware classic (somewhat modernized). There was not much logic involved in the decision making process . . . it was all heart.

This would be an excellent upgrade and is currently $2100: R14 

3080Ti, 5800X and 2 x 16 GB 3200 Mhz, 1 TB NVMe

I think you would be hard pressed to put that together for $2100 in retail parts...

Lots of great feedback.

To those comments about buying a new rig I wanted to say ultimately I have a nice gaming laptop. However, I found it's a bit too much for a flight sim in higher details and too much kit to lug around when globe trotting in my job. So, wanted a nice home based pit setup and the machine listed, though dated, was a pretty robust desktop. 

However, after reviewing all the comments, I'd like to add a wrench in the equation. Seems the Radeon GPU's run a bit better for the price points. Perhaps I am overlooking the Radeon line and getting a better performance for the price?

Pending some more great feedback.

The “ideal” MSFS AMD spec is Radeon VII, as mentioned here.

The Radeon VII is an enthusiast-class graphics card by AMD, launched on February 7th, 2019. Built on the 7 nm process, and based on the Vega 20 graphics processor, in its Vega 20 XT variant, the card supports DirectX 12.

6800XT is a more modern card.  https://www.gpucheck.com/compare/amd-radeon-rx-6800-xt-vs-amd-radeon-vii/intel-core-i9-10900k-vs-intel-core-i7-9700k-3-60ghz/

if price comparable get 6800xt, if great deal found on Radeon VII then get it.  An IT guru said always wait 2-3 years to avoid paying price premium for newest top of line gpu/cpu.

I would hold out for a few more weeks. New Radeon line up is coming out in the next few weeks. Better to wait and see what they offer.

I would not purchase any graphics card right now and wait until the new AMD video cards are released.

Apologies for delayed reply, hectic end of the week. 

I will definitely wait a few more weeks as suggested. I would love to hear feedback on this final question. 

Since I have 2 1080GTXs in SLI, will there be significant performance by just upgrading to 1 newer card instead of an SLI configuration? I am leaning towards the 3070/3080 or Radeon VII drop on their older models in a few weeks. 

With GPU prices still very strong, I am likely only buying a single GPU. By the time its ready to retire, so too will the entire machine.

Thanks for all the great info. You're my heroes.

Gpu SLI was in vogue back in 2008 but nowadays it does not help gaming as games these days do not take advantage of Nvidia’s old sli technology.  One thing we know for sure is that gtx 1080 sli does not equal twice the gpu power or speed of one gtx 1080.  The gain is modest to say the best.  The cost these days totally dissuade people from buying two identical high power gpu in sli or crossfire.

”If one GTX 1080 is 100%, two GTX 1080s will not give you 200%. Or even 150%. The truth is you’ll get something closer to around 115% to maybe 125%.”

this link says it better

if you’re gaming, having an SLI setup doesn’t make any sense. It’s extremely expensive, lacks support both from developers and Nvidia/AMD, with most games not even working with SLI setups. On the flip side, for rendering, mGPU setups can be worth the price. But only in selected applications.

SLI is not really supported anymore, and games need to be optimized for it to fully use it. Much better off with a single card.

As far as performance, depends on what you call significant.

You guys are the boss! I greatly appreciate the fact you've taken the time to help an old warrior wade through the information. 

I will indeed opt for a singular GPU. It's interesting how old habits die hard and keeping an SLI rig was one of them, which is why I opted for the 1500w PSU. I guess the other old habit in need of kicking is to stop buying Alienware desktops. While I love them initially, especially the cases, too much is not upgradeable like the original Alienware was back in the early 2000s. 

However, I love their laptops and will continue buying them. Great for travel.

Alienware desktops are akin to a gaming console: They work when you turn them on, and if you need a better one you basically need to purchase the next generation, as being upgradable is not their strongest point.

They have tried with the newer generations to make them "more upgradable", but in my opinion that is a bit of an overstatement. It's often still limited and if upgradability is something your next machine needs to have, I would be inclined to say there are better options out there.

Agreed Professor Wood, regarding the inability to upgrade Alienware MBs, kinda liek they ripped a page from Dell's playbook (tongue in cheek, I know they are part of Dell). This is my 2nd Alienware desktop and had at least 3 XPS one's before this. They all lacked an ability to upgrade their motherboards because they purposely chose proprietary equipment. Since I returned to the US in 2019 and no longer have access to a local Fry's store (out of business), I really haven't given much thought into building another desktop. It was indeed nice to walk into a store, review all available desktop kit available and to have multiple talented sales people showcase their wares. Anyway, strolls down memory lane only make my willingness to upgrade more pronounced. Will stick with a GPU upgrade for now and maybe this upcoming year, start buying parts for another home build.