I mean we can both compare notes easily, there are tons of benchmark sites which will tell gaggles of useless data. But my reason for picking AMD is largely due to the Open Source friendly nature.

I just meant that I could be talking bullshit without knowing, since I haven't been paying attention to AMD GPUs in a long time.

But I got your point. :)

Looking at the picture is indeed single slot. Is a GT 1030 too week for the games you play?

Had a look online and found some pictures of your model's motherboard (shamefuly stolen from a Ebay listing) and it seems compatible with ATX cases.
The power supply connector may need some modification or a adapter. The power switch seem simple enough but you will loose front panel audio and some USB connections.

Looking at Dell's website, there was the option to get a video card, like the AMD R7 450, so the PCI-e socket is not power limited and can run a GTX1650 without major problems.

That said, what about selling that computer and using the money to help build one yourself, the cost shouldn't change too much. That way you can have a more powerfull computer with similar cost. The i5-6400 is still a good CPU but if you want to run some modern games, it can struggle a little...

Some exemples are the i3-10100f/Ryzen 3100/3300X or a i5-10400f/Ryzen 3600.

Normally, a good idea. But remember, the OP lives in Brazil, land of absurd Import Tariffs.

As I said before, I already have a main gaming laptop (core i7 7700HQ with 16GB of RAM and a GeForce GTX 1060). The idea is to have the Optiplex with a slightly weaker GPU for city builders, RTS, etc.

From what you said (after the quoted post), I could get a new Tower and PSU and get an even better GPU and it would work. Which is nice, but I don't think I want to invest that much.

As Darvond said, our taxes suck and, quite frankly, our merchants are all scalpers. People love turning normal everyday things into highly expensive elitist stuff, simply selling it at extremely high prices. I don't really want to spend a lot right now.

Furthermore, from what I could gather online, the way the tower is built, a GTX 1650 simply won't fit in it. So I may end up getting a 1050 and seeing how it handles my games.

A friend from the company who also bought one of these machines, got a GT 1030, so I know it works alright, but I kind of want a bit more.

The desktop version of the GTX1650 is roughly the same performance as the laptop variant of the GTX1060.

As far as I know there aren't any GTX1050 single slot and low profile. The most powerfull option readily availabe is indeed the GT1030 (please note that there are some cards with DDR4 instead of GDDR5, those are much slower)

Really? That's terrible. :(

I suppose there isn't anything better on the AMD side, is there? (I understand nothing about AMD/Radeon GPUs)

You have some worksation cards like those mentioned on Darvond's post. The best performance in low profile/single slot seems to be the wx 4100, however good luck finding one at decent prices, compared to gaming cards. You can search the nVidia Quadro series as well, but the price and availability may be pretty much the same.

I see. So I guess it's either the 1030 or be prepared to invest a lot more to get a new tower, PSU and motherboard (I don't think I will keep the dell one in this case) besides a better GPU.

In any case, thank you and everybody else for the tips, ideas and help. You guys are great! :)