So I decided to build my first PC, since I wanted something better than integrated graphics for once for gaming and video editing. Originally this was supposed to be the "most smallest budget build I can squeeze out of at most $900", but about the time when I planned out everything was also when AMD and Nvidia released Navi and Super, so that was a huge monkey wrench in my plans, especially for graphics. About halfway this build transitioned to a more premium build, exemplified by the 2060 Super and the SG13.
I will explain some of my parts choice.
I made this list around the same time when Ryzen 3 was released. Why I went with a 2600 was because of price. The games I run aren't that CPU intensive, and most of my other work rely more on the multi-threaded performance of the 2600's 12 threads. The 3600 was better, but it didn't justify the extra $80. Even as this build transitioned away from a budget build, I still decided to keep the 2600 because it was good ENOUGH. I plan on more undervolting rather than overclocking in the future, but I wouldn't have that flexibility if I went with Intel's closest equivalent, the i5-9400F (there's also the thread count).
This was the lowest I've ever seen a 2060 Super. Originally I wanted to find a cheap 2060, but the release of Navi/Super ruined that plan. I would've bought Navi because of its better performance proposition, but I also wanted to try ray-tracing, and some of Nvidia's features were worth the price. Also contributing to choosing the Super was power draw, the lack of availability of 3rd-party Navi cards, and the 5700XT running way too warm. A Vega card would've also fit the place well, but I wasn't that comfortable with my PSU, and the Super card was already cutting it close compared to my original plan of a normal 2060. For a budget build though, I would go with a 2060, as there are plenty of sales of the 2060 because of the Navi/Super releases, and they can go down as low as $280. In the future though I would totally consider a Navi card, since I made a build for one of my friends, and his reference RX 5700 is doing wonders.
I will admit Gigabyte's MOBO isn't the best Mini-ITX B450 board out there, but it came with Bluetooth 5.0, built-in wifi, and a pretty good price. I would imagine that B450 prices would be going down now that X570 is out though, but I can still upgrade to Ryzen 3 with a BIOS update, and the Aorus Pro has a heatsink for the m.2 slot.
NVMe wasn't necessary, since there's not that much of an improvement compared to a SATA SSD, but I had laptops with either NVMe or SATA, and having your OS and others on NVMe did feel nicer sometimes, so my Windows 10 goes on the Sabrent, and my larger files on the ADATA. The ADATA SU635 I believe is cacheless, so I wouldn't recommend it for a boot drive, get one of those cheap TCSunbow SSDs instead. I've bought many of them and their performance is pretty good with a cache, if not inconsistent between SSDs. The Sabrent runs great, and feels as good one of my laptops that have a Samsung 960 Evo, and the ADATA is average, about what you would expect.
The build process was not that straightforward, because the SG13 doesn't really have that much space. However, everything managed to fit with some space, the AIO was able to squeeze in without any kinks in the tubes, and my fear that my 270mm card wouldn't fit the 266mm GPU clearance was nullified, as the case had no problem, just beware that anything longer may require some case/GPU modding. I ended up putting my SSD on the side inside, since the drive mount interfered with the power connector on the GPU, and I didn't want to take any chances. The PSU does draw air from up top, so even at load it doesn't seem to run like a flaming hamster wheel. Because of the massive amounts of cables though, the build initially had temps up in the low 80s because one of the cables was jamming the fan for the radiator.
Once that's resolved though, temps were normal, 45< degrees on the CPU at idle with a more aggressive AIO pump curve, and at load it never reached over 80. I did use some Noctua thermal paste I asked from a friend instead of the thermal paste upHere includes in the box, so your mileage may vary.
(I later threw in a $25 240G TCSunbow SSD for a Linux installation as it has a DRAM cache. I've had good experiences with their SSDs, although I've seen them have much higher read and write than as advertised on some units, so your mileage may vary for performance, don't get your hopes up.)
As to why this is a bad idea, here are some things I'd do differently next time.
The only reason I bought the Seasonic S12III was because there was a massive rebate on it that drove its price down to only $20. As I was originally planning on buying a cheap $20 Rosewill case, this wasn't an issue. However, with the SG13, the extra cables where a big pain in the butt. Everything fit, but having extra cables isn't that good for airflow, and with a SFX PSU + Bracket you would have more space for, say trying to fit an additional 3-in HHD.
Once again, my PSU choice was because of the ridiculously low price. However, buying a 500W or greater would've given me some future breathing room in upgrading. To be clear though, the 450W seems to be doing fine, with Aida64 combined stress tests seeming to run without issues.
A blower-style GPU probably would improve thermals for the 2060 Super, since there are cables currently blocking the top of the graphics card. Thermals are not an issue though, since the card idles around 50, and I've never seen it go over 80, even on Furmark. Also a slight complaint about the case, most reviews said it went for $44, but the cheapest I can get on Amazon was $58 (for the front with grilles, I got the flat-surfaced version), so inflation I guess? Get the $58 version if you want better airflow, but considering there were only 1 fan, I wanted a flat surface for a more subdued look (until in a few months I start putting random stickers on it >_<)
In the end, apart from the slightly noticeable fan, I'm very happy with this PC. Video editing has never been better, and running Cities Skylines on max detail, 4K without having it lag as your city expanded felt really awesome. It's a tiny case that looks cute, so I can fit it almost anywhere, even on a small desk. It doesn't look "gaming", and the only "RGBarf" was the mobo lights, which I turned on to white to illuminate the inside of the case to check the system fan. Thermals are okay, not exceptional, but not atrocious either. I guess one of the magic things about this build is that it's still about $180 less than what PCPartPicker officially suggests for a Ryzen 5 3600, so you definitely have the budget overhead, although my PSU was extremely cheap, so most of that overhead might be spent on a better PSU.
Update: 1)The graphics card bricked at anything DX12 for some reason, EVGA was pretty fast with their RMA though, and the RMA card is working fine. 2)I changed the orientation on the AIO and managed to get much better temps (for some reason). If I by default max the AIO pump and fans, I can get idle down to sub-40 degrees, and at load never over 70 degrees, although with the fans off and a less aggressive AIO pump curve it idles in the 40s while web-browsing, so this thing can be silent for casual use.
P.S. All prices here includes rebates