Game still unstable (long post)

Yay we have a winner! I'm shocked I was able to download anything since my internet had been spotty today at best, but the nvidia inspector has worked. My fps have not gone past 56, so I should be good. I am aware that Beach City will probably implode after a few generations, but I'll be bored of it by then and my sims will move via the porter mod. Thank you again for all your help, at the very least my graphics card should survive now

You know, I'm getting a little tired of providing assistance here only be told that players are shocked when something actually works. You can all take your games and...(re-reading the post above) oh, that's not what you meant at all. Never mind. :p

Just kidding of course. You're welcome but I think I need a vacation. o:)

Ha Ha! I think you more than deserve a vacation for all you do here. I know it's very much appreciated by all of us :)

The most important things that need to be done for your hardware set, if you haven't done this already, are to cap the frame rates and check the fps rates in-game to make sure they are staying capped. Unlike TS4 and other newer games, TS3 has no built-in fps limiter. Uncapped frame rates will run wild with that card otherwise and can lead to graphics glitches, lag, screen tears, crashes, and can ultimately burn out your card by making it work much harder than it should for no reason.

To check: ctrl+shift+C to bring up the cheats console, type fps on (enter). As you play and move the game camera around, the displayed fps rates should never exceed the refresh rate of your monitor. Most are 60 Hz, so 60 fps but some monitors and laptop screens can run higher. To make the displayed rates go away, cheats console again and fps off (enter).

To cap the frame rate, the first tool to try is the Nvidia Control Panel that you would already have to arrange for vsync. Note that you must create a profile for the correct executable, that's TS3.exe for Patch 1.69 but TS3w.exe (with the "w") for 1.67. Also note that the Control Panel method with vsync only works in full-screen mode. Here are the instructions with visuals: http://forums.thesims.com/en_US/discussion/comment/15007970#Comment_15007970

If this doesn't lock things in or if you require windowed mode, we move on to other tools to make this work like Nvidia Inspector or RivaTuner Stats Server (RTSS).

The game not picking things up smoothly at higher speeds is an issue most of us face after a while, but it shouldn't be quite as bad as you have described.

The game bouncing while scuba diving is a bug, or at least it often is especially if exploring underwater caves is part of the scenario, that can be solved with mods: https://sims3.crinrict.com/en/2013/06/sim-resets-when-exploring-a-underwater-cave.html
(This subsequent link to Shimrod's mods at The Asylum requires an Asylum account first and one must be logged in to see anything of substance there)

Your game seems a lot like mine.

Speed 2 and 3 are overall about the same mainly because speed 3 hitches and freezes so often. This may be a NRaas SP side effect; I recently played without NRaas SP enabled and speed 3 worked fine for long stretches of time.

Teleported while diving happens to my sims quite often. I once suspected that it was due to them autonomously deciding to use the Multi-Tab 600 in their inventories while diving and so removed those. That kind of helped. I could be wrong about the association. This may simply be another TS3 bug.

EC 12 is plaguing my current game, and sometimes the game will crash on multiple save attempts when EC 12 hits. I save about every 30 min, and for my current game I quit to desktop and reload every 1-2 days (in-game). My current game is a rather long one though. This behavior isn't typical of new games for me. I suspect the crashing in my game is due to some CC, but I don't have any idea how to find out which it is. Sometimes my game is fine for months, and sometimes it crashes 3 times in a day. At this point I'm just resigned to it and try to soldier on.

I haven't had any white lines/tearing. I have the framerate capped to 60 frames per second. Capping framerate can really help performance. You didn't mention whether you are currently capping framerates.

You mention scuba diving. Are you playing is Isla Paradiso? If so, I hope you are using the fixed up version or followed some tutorial to fix up that world. The default version is notorious for lag.

Thanks for the help
The world I'm playing is Beach City, it's large so I can live with the game clock lag. I never really played with the scuba diving so I was unaware of the bug, good to know. I'm mostly annoyed with the error 12 and crashing. Vsync is on, and my fps seem to still be the issue as they go between 42 and 100 despite it. What would be my best bet for fixing that?

If the Nvidia Control Panel isn't locking things in, then the next tool to try is Nvidia Inspector.
http://www.guru3d.com/files-details/nvidia-inspector-download.html
(the real download is 2/3 of the way down the page, not anything that might show in the upper right corner or elsewhere if you have no adblocker on your browser)

Here is a visual of its settings: http://forums.thesims.com/en_US/discussion/comment/16114546/#Comment_16114546
One thing is missing in the screenshot, though. In addition to Vertical Sync being set to Forced On, the one for Frame Rate Limiter at the top of that section should be set to 60.

While this is the most important thing to get and have stay fixed, Beach City is indeed a very large world. You may find that it is unplayable after a while as no matter what anyone does the game will Error12 if it tries to reach for more RAM than the 3.7 GB flash point. The true danger zone for most of us is somewhere around 3.4 or 3.5 GB. Very large worlds will use more RAM and keep reaching for more as they progress but a 32-bit application like TS3 has that limit that cannot be overcome. The best we can do is adjust gameplay to stay within that limit.