I'll add myself to the list of Fractal users, my primary Unraid rig in a Meshify 2 XL with 16 total drives (12 in the main "tower", and a pair each in the bottom two drive cages), and a Meshify 2 with 13 drives in it (I'll explain).

The two drives in the rear, bottom cage (disk 10 and 13) are the warmest and idle around 39 C in my Meshify 2 XL. I just decided to throw in a USB-powered fan above those drives to see how much of a difference it makes hence the one is at 37 C, which is the top drive in that cage. My server is in a generally low state of activity when I took this (5800 X with a Noctua DH-12L and a pair of fans, 128 GB RAM, pair of NVMes and a pair of 2.5 SSDs in the rear, Quadro P2000, and LSI-9300-16i). The room is around 74 C at the moment and I do have other gear in here (network rack, PC, a few Synology servers and expansion units, and a few laptops) and is the warmest room in the house because of all of this gear. I'm currently running Noctua 140mm fans in all locations, 3 as intake on the front, one intake and one exhaust on top, and exhaust on the rear. I use a plugin to control the fans to target a temperature of 35 C for the spinning rust.

Yes, I know I said 16 drives and there are only 15 at present. My second parity is currently heading back to goHardDrive for an RMA.

I run 13 drives in my Meshify 2, with 9 in the case tower, and a pair each in two drive cages in the bottom. I have a Corsair SHIFT PSU with the side-mounted connectors so I could afford the space to add a second cage and squeeze in two more drives. This is the Meshify 2 RGB so I decided to deck out all fan positions with the Fractal RGB fans, configured like I did with the Noctuas on its big brother, but this server is in a slightly cooler room with better overall airflow and running a 5600G and stock AMD cooler, 48 GB of RAM, an LSI 9207-8i, and the remaining disks connected to the Asus TUF X570 Plus mobo's SATA controller. The hardware is generally milder in this machine and performing secondary storage and has slightly lower demand so overall runs cooler. Disk 7 and 8 are in the rear-bottom drive cage as you may have guessed by the temps:

One final aside, and sharing as advice to any other HBA users, I have an adapter kit in each case that I got off Amazon for like $10 that allows you to pair up two 80mm fans (I bought like a half dozen Coolermaster fans) to cool the card above (or below, depending upon fan orientation and placement of the fans) and install them in a PCI mounting slot and power the fans off the motherboard headers with a Y-adapter. This setup is no taller than any other typical expansion card and only uses a single slot in your case to minimize the waste of expansion slots on your motherboard. I absolutely recommend this approach (or a similar directed airflow setup) to maintain adequate cooling for your HBA. For long-term stability, reliability, and lifetime of the hardware, and to keep performance from throttling, (not sure if these cards throttle but I'll never run into that), you must keep them cool with auxiliary cooling as the heatsink alone is not sufficient and they require active airflow to maintain longevity. A buddy of mine has cooked several cards because he also ran "desktop" cases like these that don't use server-style high airflow configurations that allowed his cards to run too hot for far too long.

Thanks Thanks @SimonHampel and @spasmonaut for your quick responses. Very helfpul!

I always hit the button to go with a Meshify. I now changed my view though. I realized there is a totally different option. Below has a much smaller form factor and also seems to have at least as good (likely even better) cooling. There are a few others out there with similar size and specs. This seems like the best way for me to go. Not as nice as thye Meshify, but still seems nice & clean (and smaller).

https://www.alibaba.com/product-detail/Fanlong-12-bay-half-height-NAS_1600905481914.html

Any thoughts? Anything I am overlooking?