I'm not sure where to post this. I'm new here. 

I just recently upgraded my system with some new hardware and such. Here's what I have:

Optiplex980 desktop PC, 2.9GHz CPU, 16GB RAM(MAX), GTX980Ti GPU with 4GB VRAM, I have fsx installed on a 250GB SSD. I'm flying mostly default planes, I do have a few 3rd party aircraft and ground vehicles, but al have worked fine in the past.  Ok, before the upgrade I had only 12GB RAM ,a 2.4GHz CPU and a GTX960 1GB VRAM. FSX ran ok on that but only gave a FPS of 8 or 9. Why am I still getting low FPS around 9 or 10 sometimes maybe up to 16 if I ain't movin' . I've set all my sliders to min and still get low FPS. I thought with all the upgrades it would at least improve some, I'd be happy with at least 20FPS, but 9 is ridiculous. I've tried out the 'tweaks' and still no improvement. Is there anything else I can maybe do to improve my FPS? It's really hard to take off and land with 9FPS because of the serious stutters. Daytime flying seems to be a bit better than night flying. Daytime gives me about 18FPS which is tollerable, but night drops down to 9FPS. I've tried about everything I can think of to fix this. If this system isn't going to support FSX any better than this, I don't want to pump more money into it. I'd rather just save my money and buy a new machine specificly for FSX (at which point I would upgrade to a newer FS).

Your first thought was right, there is a forum that specialises in addressing concerns like yours:

https://www.avsim.com/forums/forum/326-system-hardware-pc-mobo-ram-cpu-hdd-ssd-psu-etc/

I like computers but I can't give you the sort of advice you're looking for.

If you leave your post as it is it will be moved to the hardware forum by the moderators which will save you having to copy and paste your query to the link above.

In any case, welcome to the FSX forum and good luck.

Which version of FSX, one of the boxed versions or the Steam Edition?

Boxed FSX Acceleration 

I looked up the system specs of your Optiplex 980 and saw that it is about 15 years old. It's a business computer not well suited to gaming.

I try to keep all my old computers, so I know that they become difficult at that age. I know that you can upset some of the system functionality when you go swaping parts during an upgrade.

You mentioned buying a new computer. I would be thinking about saving up for a new computer if I were you. It wouldn't need to be too powerful if FSX is the only thing you want to run.

Two things.  Yes, the Optiplex is a business computer, so it cannot be expected to run flight sims all that well.  Second, the boxed versions of FSX do not run as well as the Steam Edition.

It did used to run fine, It has an i7 2.9GHz CPU (the stock CPU was ai5 2.3 GHz) I've done a lot of upgrades over the years. I know this thing is old, and I will be saving up for a newer system in the near future. I'm looking at maybe getting a AMD system specifically for gaming. It's gonna run me a good $2K or so. I'm not expecting mirracles from this one, but SFX has been running fine with at least 22FPS for a good long time, it's just recently started giving me poor performance with low FPS. I have noticed that my weather app seems to affect it a bit. I turned it off and my FPS went up slightly to about 12-16 FPS. I'm running the older version of FS Real WORLD WEATHER. I tried to upgrade to the newer version, but for some reason it won't run, it says my FSUIP is outdated and I have the latest version installed. I was thinking of trying Active Sky, does it run better than FSRWX? I noticed that when FSRWX is updating the weather it causes FS to stutter really bad. Does AS do this? If AS is better, then I may just upgrade to that. But still can't figure out why a month ago my FPS was a good stable 22-24 FPS and now they are down to a max of 16 FPS. I've shut down all background apps and un-necessary services, but no improvement. I have re-installed FS due to some serious issues with the old copy. But it was running fine until now. I've added the 'tweaks' into my .cfg as well, however, I used the 'suggested' values because I couldn't remember the values I originally had. Which one of the 'tweaks' would affect FPS the most? It would be helpful to know which one I should be concentrating on. If I can get a good 22 or 24 FPS I'm satisfied until I get a new system. With all of the current upgrades I have on this thing, FS should run fine, not going to be great, but should be fine. I've been 'flying' on this thing for years and it never gave me this much trouble.

6 hours ago, TomT478 said:

...I tried to upgrade to the newer version, but for some reason it won't run...

This sounds like a pretty good indication your system is failing.

Which version of Windows do you have?

Those Optiplex PCs came with tiny low-end OEM 255W power supplies--the RTX 980Ti's design thermal power alone is 250W.  Do you have two separate power cables (not a daisy-chain cable) going to the 980Ti's aux power connectors?  From the pics I've seen, the Optiplex PSU did not have any additional VGA power cabling--it was designed for a half-length discrete video card powered by the PCIe bus alone.  I'm surprised the 980Ti would even fit into that case.  Anyway, if you're running that video card without sufficient power available, it might explain a lot.

Yeah I upgraded the PSU to a 1000W, Dual fan unit. I have two CPU fans,and I added a case fan. The card is a full length card but it just barely fits in there. I knew it would fit because I used to have an AMD 6800 series card in there. I did have to replace the CPU fan today, it was failing ,at least the main one was. It was running a bit slow and the CPU was cycling down to protect itself. I replaced the fan and it's running a lot cooler now. I am getting up to 18FPS now. I used PC Cleaner to do some 'housework' on the system and it's running at optimal speed and performance at this point. I'm still not getting my usual 22 FPS like I used to except when sitting still at the gate. This seems to have happened when I had to do a re-install of the sim due to some kind of file corruption. I don't know if I missed something in the .cfg or what. 18FPS is ok for some of the smaller planes and the A320 seems to fly ok. I tried out one of my addon aircrafts ,it's one of those space planes, I forgot the name of it, but it actually works better than most of the stock planes. It uses the textures and guages from the 747 ,so I am going to try flying with one of the 747 jets and see what my FPS do. I do think you may be right about it being a system failing issue and I'm currently trying to track down anything that may be failing and fix those first. I have a 1000W PSU but it's about 4 yrs old now and I wonder if maybe it could be wearing down and needs replacing. I have a tester that tests PSU performance and I think I will go in and run a test on it to make sure it's doing what it should. I know from past experiences that a failing PSU can cause issues and in some cases cause overheating. I am a Certified Electronics Technician and I can handle whatever this old thing can throw at me. But as far as issues with FSX, that's software and I'm no software professional so I leave that to those who know what they are doing. Oh and BTW I am running Win11Pro, hence the reason for upgrading the CPU. The stock one wouldn't even allow win11 to install. I had to research to find out which one would both work on my MB and one that was compatible with Win11. Not too many of em' are, only about 4 are compatible.

 I am considering actually just custom building my own system from scratch, I'm researching now for high end MBs and CPUs that can handle serious gaming and even VR. 

Have you tried running the System File Checker?

Open command prompt as administrator and type:

sfc /scannow

Yeah, building is fun, but my experience has been that you only need a pricey MB if you intend to do overclocking, otherwise a cheaper one is just as good.

I did run the file checker, everything looks good asside from a couple of files from another program that were unused.

I did a complete system scan and cleaning using PCcleaner. It helped somewhat, I get up to 29 FPS occasionaly.  My only problem is the FPS is all over the place, jumps from 9 to up to 29. It really drops when I taxi and have to turn, drops to 8 sometimes. It never used to do that, I always had a good 24 FPS steady. Sometimes I could even get up to the 32 on certain aircraft. I'm starting to wonder if possibly there is a remnants of something I installed and it never got completely removed. I know I installed ORBX once, and it dropped my FPS all the way to 2 so I promptly removed it. It may be possible that some of its stuff may still be in there. I need to look at all my cfg files and see if any ORBX stuff is being accessed. I would think that re-installing FSX would just ignore ORBX and not add it or anything. I'm in the process of examining everything by hand ,file system, programs, removing stuff that is no longer in use, etc....I'm also going to run a full check tonight on my SSD to make sure it isn't failing in some way. I had already replaced it once because the old one died. I put in a more reliable one this time around, it's been in there for about 3 years now.

I don't really plan on overclocking anything, I found that causes more problems than it's worth. I will most likely go with a good middle of the road ASUS MB and an AMD RYZEN CPU with a good high end Nvidia GPU, probably get a 1TB SSD for the main system and a 500GB for FSX alone. All other drives are HDs and are external so I shouldn't have to mess with them.

I'm never going to be in a position to consider overclocking because I live in a warm climate. I can't even run the sim today because it's too hot, about 28° C.

ASUS has the best reputation, but there are plenty of others you might consider. AMD CPUs are most popular at the moment and well priced, and Nvidia is as well, but they're pricey. If FSX is the only sim you want to run then it won't need to be too high end.

I've got a Radeon 7900 XT for my MSFS 2024 rig and it performs nicely. It's amazing how strong computer parts are nowadays.

I know, I used to run a AMD 6800 GPU on this thing and it actually ran better than the Nvidia 960 I had in here, I have a 980 now, but haven't really seen any improvement in performance. I am actually thinking about buying the parts to repair my old AMD card, it just needs a fan on it, and consider putting it back in here and see what happens with performance. Luckily I have the mini-tower Optiplex 980 machine instead of the slim tower, so full length cards actually fit in this thing. Another thing I think may have affected performance is when I upgraded to Win11, FSX ran great on Win10, but because support for Win10 ended ,I had no choice but to upgrade which meant upgrading EVERYTHING including the CPU, just to make it compatible with Win11. That seems to be the point where performance started to deteriorate. I'd love to get this thing back to its original performance, without having to dish out $2000+ for a new machine just to run a sim on. FSX used to run so nicely on this machine even before any of the upgrades. I bought this thing online for $180 12 years ago, it was just the stock machine with Win7 on it. Had an i7 2.4GHz CPU and 4GB RAM, I put in the AMD 6800 Radeon card, and FSX ran just as good on it as it would on a high end gaming machine, never gave me any problems. Those were the good ole days. My brother gave me FSX Acceleration as a gift and I was hooked the moment I installed it. I'd love to see it run as it did back then now with all the extra addons and improvements in some of the textures and things. I just don't think I can solve the FPS problem. I've done all the suggestions given here and online, but either they don't do anything at all, or they make it worse. Just don't know what else to do from here. Like I said, I may just go back to the AMD Raedeon 6800 card and see if anything changes. This machine may just not like Nvidia. I have heard some people have had compatibility issues with Nvidia and Intel CPUs, they don't like each other for some reason.

16 minutes ago, TomT478 said:

Those were the good ole days. My brother gave me FSX Acceleration as a gift and I was hooked the moment I installed it.

You got that right. I've got three versions of P3D, MSFS 2020 and '24, but I keep coming back to FSX because it's so much fun. I can tinker with the configuration files and make it do whatever I want which is something '20 and '24 won't allow.

I was thinking years ago when ACES Game Studio got shut down that one of the reasons was because FSX was perfect. They figured that they just couldn't improve on that.

Yeah, that 6800 might have some life left in it, and if you've got the skills you may as well try. It's only about five years old.