I threw this together 2 years ago as an offsite backup server. The goal was to push the limits of the N400 chassis, and attempt to install 18 3.5" drives. I had the CPU, motherboard, memory, and power supply lying around from another project. 12 of the 3TB drives came from a previous NAS I had, and the remaining 6 were purchased from a friend. I was under time pressure to complete this build, so it remains very unpolished.
At the time, I had a working theory on how to cram 5 additional 3.5" drives into the optical drive bays in the N400. After looking through many of the N400 pictures available online, I was pretty sure this plan would work.
Pics
I know the cable management is awful, follow the recommendations below to avoid my fate.
General theory
While I did manage to squeeze 18 drives into my N400, I wouldn’t recommend anyone actually use the vertical mount. That leaves us with 16 3.5" drives, and 15 if you leave out the bottom bonus slot with poor airflow.
Drive location breakdown
- 8x 3.5" drives in the 8 stock 3.5" bays
- 1x 3.5" drive below the stock 3.5" bays
- 5x 3.5" drives in the 2(.75) 5.25 optical drive bays
- 2x 3.5" drives mounted to the side intake fan mounts
- 2x 3.5" drives “mounted” vertically to the PSU (not recommended)
Optical bay drives
The drives located in the optical bays are secured with something similar to the “5 in 3” drive cages available for sale. I designed and 3D printed a custom cage to make this work. Each drive has two plastic sliders screwed into it, and the drives slide in from the inside of the case. This isn’t the greatest design, since I can’t really take out the drive closest to the motherboard without removing said motherboard 
. A 120mm fan is mounted on the front of the cage to provide cooling to the drives.
Looking back at the photos, it looks like I had to bend back the metal tabs that usually support the top optical drive. Easily solvable with a pair of pliers
Side mounted drives
The drives located on the side intake fan mounts were enabled by two 120mm fan to 3.5" drive brackets I also designed and 3D printed. They screw in to the drives from the bottom, and are mounted in the 120mm fan slots. Cooling could be better here, but there is plenty of room for mounting some slim fans.
PSU “mounted” drives
I screwed some custom 3D printed brackets into a plate I attached to the PSU. The drives aren’t really secured in the vertical direction, so they will fall out if you tip the machine over. This is objectively a bad design and a bad spot for these drives, please don’t do this. I’ve since removed mine from this spot.
Specs
| Part | Model | Price | Source |
|---|---|---|---|
| CPU | Intel i7-8700 | had | had |
| MB | MSI Z370 Krait Gaming | had | had |
| RAM | 4x16GB DDR4 ?? MT/s | had | had |
| PSU | Thermaltake something | had | had |
| HBA | Dell H200 IT mode | had | had |
| Case | Cooler Master N400 | $90 in 2022 | Amazon |
| Expander | Dell 5R10N | ~$30 in 2022 | eBay |
| Drives | Seagate 3TB | $25 each in 2020 | Someone on reddit |
| Cable | SFF-8087 to (4) SFF-8482 breakout cable | $13 each | eBay |
Lessons learned
- The specific SAS expander I used made the cable management difficult
- Don’t use a SAS expander at all, get a 16i HBA and be done with it - ASR-71605 was OOS when I was building this
- If a SAS expander is necessary or desired, get an HP style one and shove it in the least important PCIe slot
- The drives in the 3D printed cage should probably come out the front
- This isn’t 100% trivial, as there is a metal lip on the front of the case the drive guide will need to clear. This lip could be moved, or the drives could possibly be offset more towards the bottom of the cage
- Don’t mount random stuff to the PSU (it got the job done though)
- Don’t attempt the 18 drive config, 15 or 16 is the sweet spot
- All hail N400
Recommendations
I would wholeheartedly recommend the 15 and 16 drive configs in this case.
If anyone is interested, I can look around for the CAD files for the 3D printed parts. I know I still have them, I just haven’t had a chance to look
