A QNAP TS-464eU is 292 mm deep, idles at 21.1 W with its drives spun down and costs about $850. That makes it the best rackmount NAS for most homelabs and small offices with a shallow wall cabinet. Check depth first, because a 1U chassis that looks compact in a listing photo can run 480 mm deep before the ears and power inlet are counted, and many 19-inch network cabinets cannot take that.
We ranked seven short-depth 1U and 2U units from QNAP, Synology and TerraMaster by depth, standby power per bay and upgrade room: 10GbE, NVMe cache, memory and a second power supply. None were powered in our lab, so every figure is a maker figure. The deepest pick, the TerraMaster U4-500, still stops at 381 mm (spec sheet and Amazon price checked October 2026). Steps 3 to 5 cover the rail, drive-policy and power checks that decide whether a unit works in your rack.
Best rackmount NAS units ranked by depth and idle power
All seven fit a cabinet with 400 mm of usable depth, and six stay under 330 mm. Standby is the maker figure with every bay full and the drives spun down, which is where a homelab NAS spends most nights. Access is the same test with the array busy. QNAP measures depth on the chassis alone, without the ear hooks or the protruding power supply, so allow extra depth beyond the listed figure for the QNAP units.
| NAS | Size | Depth | CPU | Onboard network | Standby / access | Price (approx.) |
|---|---|---|---|---|---|---|
| QNAP TS-464eU | 1U, 4 bays | 292 mm | Celeron N5095, 4 cores | 2 x 2.5GbE | 21.1 W / 35.3 W | about $850 |
| QNAP TS-435XeU | 1U, 4 bays | 292 mm | ARM Cortex-A72, 4 cores | 2 x 2.5GbE, 2 x 10GbE SFP+ | 17.4 W / 30.9 W | about $890 |
| Synology RS422+ | 1U, 4 bays | 328 mm | Ryzen R1600, 2 cores | 2 x 1GbE | 13.4 W / 37.9 W | about $800 |
| TerraMaster U4-500 | 1U, 4 bays | 381 mm | Core i3-1215U, 6 cores | 2 x 10GbE RJ-45 | 18.9 W / 40.2 W | about $900 |
| Synology RS1221+ | 2U, 8 bays | 307 mm | Ryzen V1500B, 4 cores | 4 x 1GbE | 22.6 W / 49.9 W | about $1,650 |
| QNAP TS-864eU-RP | 2U, 8 bays | 297 mm | Celeron N5095, 4 cores | 2 x 2.5GbE | 31.7 W / 55.8 W | about $1,700 |
| QNAP TS-873AeU | 2U, 8 bays | 297 mm | Ryzen V1500B, 4 cores | 2 x 2.5GbE | 26.8 W / 52.5 W | about $2,010 |
Read the table by the job the NAS has to do, then jump to that pick:
- Best overall short-depth 1U: QNAP TS-464eU, for Intel graphics that transcode, two NVMe slots and the shallowest chassis.
- Best for a 10GbE network: QNAP TS-435XeU, the only unit with SFP+ cages on the board.
- Best for an existing Synology office: Synology RS422+, DSM in 328 mm and outside the 2025 drive rules.
- Most CPU in 1U: TerraMaster U4-500, a Core i3 and two 10GbE ports in 381 mm.
- Best 8-bay for a small office: Synology RS1221+, ECC memory and a x8 slot in 307 mm.
- Best for redundant power: QNAP TS-864eU-RP, two 300 W supplies in a short 2U chassis.
- Best for ZFS and expansion: QNAP TS-873AeU, a 64 GB memory ceiling and a x8 slot in 297 mm.
Per bay, the RS1221+ draws the least in standby at 2.8 W and the TS-464eU the most at 5.3 W, because four bays carry the whole platform idle load. The two QNAP 2U units share the same 297.4 mm depth, so the choice between them is redundant power against memory and slots, which Step 2 works through.
How the seven units were chosen and checked
A unit made the list only if it is a current model sold new on Amazon US with at least four 3.5-inch bays. It also had to measure under 400 mm from front panel to rear, because past that depth a homelab cabinet stops being a wall cabinet. The numbers behind each pick came from four places:
- Specs: maker spec pages and datasheet PDFs from QNAP, Synology and TerraMaster, read in October 2026. QNAP publishes no noise figure for any of these units, so noise appears only where Synology or TerraMaster publish one.
- Power: maker figures with all bays full. Each maker picks its own test drives (1 TB WD Red for the TS-873AeU, 4 TB Seagate IronWolf for the U4-500), so a gap of a few watts between brands sits within the margin of the method.
- Prices: Amazon US listings pulled through the Amazon product API in the same week. Most QNAP listings show limited stock.
- Hands-on: none. We did not rack or power these units, so there are no throughput or temperature numbers of our own in this guide.
Two popular models fell off on depth alone. The Synology RS826+ is 492.6 mm deep and mounts on 4-post rails only. The QNAP TS-464U, one letter away from our top pick, is 479 mm deep against 292 mm for the TS-464eU. If your rack is a 10-inch mini rack, none of the 19-inch units here fit at all, and the 10-inch mini rack build covers the small NAS options that do.
Three more short-depth QNAP units qualified on size and were left out on substance. The TS-433eU (around $610) has 4 GB of memory soldered to an ARM board, and the TS-432XeU and TS-h765eU have no published power figures, which this ranking depends on.
Step 1: Pick a 1U NAS for a shallow cabinet
A 1U four-bay unit covers most homelabs, because four large drives in single-parity RAID already hold more than most media libraries and backups need, in 44 mm of rack height. The four 1U picks have the same bay count and split on network ports and CPU, so start from the switch you own and the apps you plan to run.
QNAP TS-464eU: best overall short-depth 1U
Buy the TS-464eU if one box has to serve files, run a few containers and transcode Plex or Jellyfin streams from a 292.1 mm chassis. Its Celeron N5095 has Intel UHD Graphics, and QNAP lists hardware transcoding for it, which the ARM-based TS-435XeU in the next section does not offer.
Memory starts at 8 GB of DDR4 and tops out at 16 GB across two SODIMM slots. Each of the two M.2 2280 slots runs NVMe on a single PCIe 3.0 lane, about 1 GB/s at best. That still outruns the two 2.5GbE ports (about 625 MB/s combined), so the slots work as a cache or a small fast pool. QNAP rates the unit at 35.3 W in operation and 21.1 W in disk standby on a 100 W supply, and two rack ears come in the box.
Pass on it when the network is already 10GbE. There is no PCIe slot, so the 2.5GbE ports are the ceiling for the life of the box. Sixteen gigabytes of memory is also tight for QuTS hero, the ZFS-based QNAP system, on four large drives. It sells for around $850 on Amazon at the time of writing, so check the live price before you order.
QNAP TS-435XeU: best for a 10GbE network
Of these seven, only the TS-435XeU has 10GbE SFP+ cages on the motherboard: two of them, next to two 2.5GbE ports, in the same 292 mm chassis as the TS-464eU. With an SFP+ switch, that saves an add-in card and the slot it would need, which the TS-464eU and U4-500 do not have at all.
Inside is a Marvell OCTEON TX2 ARM chip with four Cortex-A72 cores at 2.2 GHz. Memory is 4 GB of DDR4 in a single slot that takes up to 32 GB, and QNAP supports ECC modules from QTS 5.0.1. Its operating draw is the lowest of the 1U group at 30.9 W, with 17.4 W in disk standby.
ARM is the cost. The unit runs QTS 5.2 only, so there is no QuTS hero and no ZFS, QNAP lists no hardware transcoding, and apps built only for x86 do not run on it. Buy it as a fast file and backup target, not a media server. It is around $890 on Amazon right now (check the live listing).
Synology RS422+: best for an existing Synology office
Synology fits DSM into a 1U box 327.5 mm deep with the RS422+, and costs around $800. For an office that already runs DSM on a DiskStation, it joins the same management and replication setup without a second system to learn.
Two details matter more than its spec sheet suggests. It is a pre-2025 model, so the 2025 Synology drive policy does not apply and third-party hard drives can still build new storage pools. That is not true of the newer RS826+ and RS1226+. It also has the lowest standby draw in this guide, 13.4 W with the drives hibernating, and Synology rates it at 28.5 dB(A).
Its limits are real, though. Memory is 2 GB of ECC DDR4 and the spec page lists no slot or maximum, so plan on 2 GB for the life of the unit. The two 1GbE ports cap at an MTU of 1,500 bytes, so no jumbo frames, and the only upgrade is the E10G22-T1-Mini 10GbE module in a PCIe 3.0 x2 slot. Pass on it if you want containers or VMs on the NAS. The listing sits near $800 on Amazon (check the live price).
TerraMaster U4-500: most CPU in 1U
TerraMaster packs an Intel Core i3-1215U (six cores, eight threads, up to 4.4 GHz) and two 10GbE RJ-45 ports into the 1U U4-500 for about $900. Nothing else in the 1U group comes close on CPU, and its two M.2 slots run at PCIe 4.0 x4, against a single PCIe 3.0 lane per slot on the QNAP units.
Memory is non-ECC DDR5, 8 GB in one of two slots with a 64 GB maximum. TerraMaster rates it at 40.2 W under load, 18.9 W with the drives hibernating and 34.5 dB(A). At 381 mm it is the deepest pick here. The TerraMaster product description and April 2025 launch note both say 360 mm, so plan the rack around 381 mm, the spec-tab figure.
Expansion stops at the M.2 slots, since no PCIe slot is fitted. The TerraMaster FAQ states that installing another operating system invalidates the warranty. A January 2025 NASCompares report describes a TerraMaster allowance for Unraid, so check the current TerraMaster policy before you plan TrueNAS or Unraid on the 2-year warranty. The package lists neither rails nor rack ears. TerraMaster describes the mount as tool-less, so confirm how it fixes to your cabinet before you order. The 8-bay U8-500 Plus (88 mm tall, 384 mm deep, Core i7-1255U, around $1,530) runs the same TOS under the same third-party OS policy. At 90 W under load it draws more than any of the seven ranked units. Buy it for TOS on a fast CPU, at about $900 on Amazon (confirm the live price).
Step 2: Move to a 2U NAS when four bays are not enough
Eight bays in 2U double the drive count for roughly twice the price, and all three units here stay under 310 mm deep. They differ in what they protect against: memory errors, a failed power supply, or running out of memory and slots.
Synology RS1221+: best 8-bay for a small office
We would put the RS1221+ in an office closet. It pairs a 4-core, 8-thread AMD Ryzen V1500B with 4 GB of ECC DDR4 that grows to 32 GB, plus a PCIe 3.0 x8 slot (wired x4) for 10GbE, 25GbE or M.2 cards. At 306.6 mm deep with 2-post mounting support, it fits the same wall cabinet as the 1U picks.
Because it launched in 2021, the RS1221+ sits outside the 2025 Synology drive policy. That age shows in the network: four 1GbE ports and no 2.5GbE, so budget for an E10G30 card if the NAS feeds more than a few clients. Per bay it is the lowest-power unit in this guide, 22.6 W in hibernation across eight bays (2.8 W per bay) and 49.9 W under access, at 37.8 dB(A).
For faster ports, the newer Synology RS1226+ keeps the same depth and CPU, swaps the four 1GbE ports for two 2.5GbE ports, adds two M.2 NVMe slots and costs about $2,000. Its spec page states that compatible drives are mandatory, which on RackStation Plus means hard drives from Synology’s list for any new storage pool. If you already own third-party drives, the RS1221+ at about $1,650 (check the live price) is the safer buy.
QNAP TS-864eU-RP: best for redundant power
Redundant power is the reason to buy the TS-864eU-RP: two 300 W supplies, with two power cords in the box, in a 297.4 mm 2U chassis. A failed supply or a tripped circuit on one feed leaves the array running, provided each supply draws from a different UPS or circuit.
Its CPU is the same Celeron N5095 as the TS-464eU, with hardware transcoding, 8 GB of DDR4 and a 16 GB ceiling. QNAP rates it at 55.8 W in operation and 31.7 W in disk standby, and cools it with three 60 mm fans.
Compute is the weak part. Sixteen gigabytes across eight large drives is tight for QuTS hero. The single PCIe 3.0 x2 slot takes low-profile cards up to 97 mm, so it is 10GbE or an M.2 adapter, not both. The second supply only pays off with a second power source, and our UPS picks for a homelab NAS cover sizing for it. It lists at around $1,700 on Amazon (check the live price).
QNAP TS-873AeU: best for ZFS and expansion
Pick the TS-873AeU for QuTS hero, the ZFS-based QNAP system. Its memory ceiling is 64 GB, against 16 GB on the TS-864eU-RP and 32 GB on the RS1221+. It runs the same 4-core, 8-thread AMD Ryzen V1500B as the RS1221+, at the same 297.4 mm depth as the TS-864eU-RP, and supports ECC memory.
Expansion is the other reason to buy it. A single PCIe 3.0 x8 slot takes cards up to 210 mm long, enough for a 25GbE NIC or an M.2 adapter. Two onboard M.2 2280 slots run at PCIe 3.0 x1 for a small cache. QNAP rates it at 52.5 W in operation and 26.8 W in disk standby with eight 1 TB WD Red drives, on a single 250 W supply.
It ships with only 4 GB, so budget for memory before ZFS is usable. The Ryzen also has no integrated graphics, so Plex transcoding needs a graphics card in the only slot. At about $2,010 (check the live price) it costs roughly $360 more than the RS1221+ with the same CPU. That premium buys QuTS hero and the memory headroom. The 8-core TS-855eU at the same depth is not ranked, because its Amazon buy box was a used resale unit when we checked.
Step 3: Measure the rack, then buy the rails
Rails are where short-depth plans break. None of these units ships with a rail kit, and sliding rails are built for deep racks. The Synology RKS-02 needs 610 to 890 mm between the front and rear posts, and the fixed RKM114 needs 570 to 720 mm for the RS422+ and RS1221+. A 450 mm wall cabinet takes neither. The optional QNAP RAIL-B02 is listed by resellers at 443 to 815 mm for square-hole racks only, so it may just fit a square-hole cabinet, but confirm the range on the QNAP accessory sheet. Measure before you order anything:
- Post-to-post depth: decides which rail kits fit, if any.
- Usable depth behind the front rail: must cover the NAS depth plus the bend radius of the power and network cables.
- Hole type: square or round holes on the posts, which decides the rail kit and the cage nuts.
In a shallow cabinet, front ears on a 2-post mount are the realistic option. QNAP 1U short-depth units ship with two rack ears in the box (check the package list for the 2U units), and Synology lists 2-post direct mounting for the RS422+ and RS1221+. An 8-bay unit full of drives hangs a lot of weight off four front screws, so add a shelf under it. Our server rack guide lists racks by their mounting depth range.
Step 4: Check the drive policy before you buy disks
Synology’s October 2025 change that let DiskStation Plus models build pools on third-party drives did not extend to RackStation. On RackStation Plus models from 2025 on (RS826+, RS1226+ and their RP versions), an unlisted hard drive can only be migrated in from another Synology system. It cannot create a new pool, while third-party 2.5-inch SATA SSDs work with an Unverified warning. The RS422+ and RS1221+ predate the policy, and the Synology drive compatibility FAQ says it does not apply retroactively.
We found no equivalent restriction on the QNAP and TerraMaster spec pages for these units. Buy CMR drives rated for NAS use: our NAS hard drive picks rank the current options, and the CMR vs SMR explainer shows why SMR drives drag out RAID rebuilds.
Step 5: Budget the network ports and the power bill
A NAS runs every hour of the year, so its standby and access figures turn straight into kilowatt-hours. At an assumed $0.17 per kWh, the maker figures work out to this yearly cost:
| NAS | Standby | Per year at standby | Access | Per year at access |
|---|---|---|---|---|
| Synology RS422+ | 13.4 W | 118 kWh, about $20 | 37.9 W | 332 kWh, about $56 |
| QNAP TS-435XeU | 17.4 W | 152 kWh, about $26 | 30.9 W | 270 kWh, about $46 |
| TerraMaster U4-500 | 18.9 W | 166 kWh, about $28 | 40.2 W | 352 kWh, about $60 |
| QNAP TS-464eU | 21.1 W | 185 kWh, about $31 | 35.3 W | 309 kWh, about $53 |
| Synology RS1221+ | 22.6 W | 198 kWh, about $34 | 49.9 W | 437 kWh, about $74 |
| QNAP TS-873AeU | 26.8 W | 234 kWh, about $40 | 52.5 W | 460 kWh, about $78 |
| QNAP TS-864eU-RP | 31.7 W | 278 kWh, about $47 | 55.8 W | 489 kWh, about $83 |
Real draw sits between the two columns and depends on how often the drives spin down. A homelab NAS that streams in the evening and sleeps overnight lands closer to standby. Between the most and least frugal units, the yearly spread is about $27 at idle and $37 under load. The same figures set UPS runtime, which is why a 13 W unit and a 32 W unit need different batteries for the same shutdown window.
Match the onboard ports to your switch before price. The 1GbE ports on both Synology units cap any single client at gigabit speed, below what one modern 3.5-inch drive reads sequentially. Plan a 10GbE card from day one if the NAS will hold VM disks or video projects. For the switch side, the 10GbE and 25GbE switch picks list SFP+ and RJ-45 models that match the TS-435XeU and U4-500 ports.
When a DIY rackmount build beats a prebuilt NAS
Build your own when depth is not the constraint. The Rosewill RSV-L4412U from our NAS case guide holds twelve hot-swap bays in 4U for about $390 on Amazon. It is also 650 mm deep, more than twice the QNAP 2U units, and it still needs a board, CPU, memory, power supply and usually an HBA. The NAS motherboard picks cover the boards for that route, which buys ECC, TrueNAS or Unraid without warranty questions, and parts you can replace one at a time.
In a shallow cabinet the prebuilt units win, because none of the DIY cases we have covered puts eight hot-swap bays in under 310 mm. The decision then becomes the operating system. DSM suits an office that values the Synology backup apps and accepts the drive rules. QTS or QuTS hero gives the most hardware per dollar, and TOS makes sense only when the CPU matters more than the warranty terms on third-party systems. Our DIY vs prebuilt NAS comparison runs the same decision for desktop units.
