4-Bay vs 8-Bay NAS Devices: Which Should You Buy?
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Choosing between 4-Bay vs 8-Bay network attached storage depends on your capacity needs. Both units expand your storage footprint, but they differ significantly in form and function. The Synology RX418 is a diskless expansion unit designed to add bays to an existing system. The QNAP TS-673-4G is a standalone NAS with its own processor and memory. You must decide if you need extra bays or a complete system.
Key differences
| Aspect | Synology 4-Bay Rackmount Expansion Unit | QNAP TS-673-4G 8-Bay NAS |
|---|---|---|
| Form Factor | Expansion Unit (Diskless) | Standalone NAS |
| Number of Bays | 4-Bay | 8-Bay |
| RAM Capacity | not listed | 4GB RAM |
| Processor | not listed | AMD R-Series Quad-core 2.1GHz |
Which one should you choose?
Choose Synology 4-Bay Rackmount Expansion Unit if
- You already have a Synology NAS and need more drive slots.
- You want to add storage without buying a new main unit.
- You prefer a compact 1U rackmount form factor.
Choose QNAP TS-673-4G 8-Bay NAS if
- You need a complete, standalone NAS with its own CPU and RAM.
- You require eight drive bays for high capacity.
- You want built-in support for GPU transcoding and caching.
Verdict: The Synology RX418 is best for users who already own a Synology NAS and simply need more drive bays. The QNAP TS-673-4G suits those who need a full, standalone system with eight bays and robust processing power. Choose based on whether you are expanding an existing setup or building a new one.
4-Bay vs 8-Bay NAS Comparison
Number of Bays
The Synology RX418 offers four drive bays, while the QNAP TS-673-4G provides eight slots. The QNAP model includes six standard 2.5 or 3.5-inch drive bays plus two M.2 NVMe slots. This gives you significantly more total storage capacity. The Synology unit is a diskless expansion chassis. You must add your own drives. The QNAP provides a complete standalone system with more physical slots for hard drives and SSDs. If you need maximum raw storage space in a single enclosure, the eight-bay option is the clear choice for capacity.
Form Factor
The Synology RX418 is designed for rack mounting. It measures 44 mm in height, which is a standard 1U rack unit size. It fits into 2-post racks and wall mount racks. The QNAP TS-673-4G is a desktop tower. It is much taller at 7.41 inches and weighs more. The Synology unit is lighter at 9.44 pounds compared to the QNAP's 12.3 pounds. Your choice depends on your physical setup. You need rack space for the Synology. You need desktop surface area for the QNAP. The form factors serve different installation environments.
RAM Capacity
The QNAP TS-673-4G comes with 4GB of DDR4 RAM as a base specification. It also offers an 8GB RAM variation. This memory supports virtualization and containerized apps. The Synology RX418 is a diskless expansion unit. It does not have its own processor or system memory. It relies on the main NAS unit it connects to for processing power and RAM. Therefore, the Synology has no independent RAM capacity. The QNAP provides its own memory resources for handling tasks directly.
Processor Cores
The QNAP TS-673-4G features an AMD R-Series quad-core processor running at 2.1GHz. This allows it to operate independently. The Synology RX418 has no listed processor. As an expansion unit, it lacks its own CPU. It depends entirely on the host NAS for all computational tasks. The QNAP can handle data processing, transcoding, and app execution on its own. The Synology cannot. If you need independent processing power, the QNAP is the only option here.
Network Connectivity
The QNAP TS-673-4G includes four 1GbE LAN ports. It also supports optional 10GbE PCIe expansion cards. This allows for high-speed networking upgrades. The Synology RX418 does not list specific network ports in its provided data. It connects to a main NAS via a proprietary expansion cable. The QNAP offers direct network connectivity with multiple ports. You can bond these ports for speed or redundancy. The Synology relies on the host unit's network interface. The QNAP provides more flexible and robust network options.
Which NAS device fits your needs
Existing Synology users needing more space
The Synology RX418 is a diskless expansion unit designed to integrate seamlessly with your current Synology DiskStation Manager system. It offers four additional drive bays for online volume expansion. Its 12-inch depth fits standard 2-post racks, and it operates in an energy-saving deep sleep mode when idle. This makes it the logical choice for scaling your existing infrastructure without replacing your primary unit.
Users requiring high performance and flexibility
The QNAP TS-673-4G features an AMD R-Series quad-core processor and 4GB of DDR4 RAM. It includes six standard drive bays plus two M.2 SATA SSD slots for caching or storage pools. You get four 1GbE ports and two PCIe Gen3 slots for 10GbE expansion or graphics cards. This setup supports virtualization, containerized apps, and 4K video transcoding for demanding workloads.
Those building a new standalone system
If you are starting from scratch, the QNAP TS-673-4G is a complete NAS unit with its own processor, memory, and network ports. It provides eight total drive slots, including M.2 options. The Synology RX418 is diskless and requires an existing host system. For a standalone solution with robust specs like a quad-core CPU and PCIe expansion, the QNAP model is the practical selection.
Quick picks
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | Synology 4-Bay Rackmount Expansion Unit | expanding Synology NAS storage | Check price of Synology 4-Bay Rackmount Expansion Unit on Amazon |
| 2 | QNAP TS-673-4G 8-Bay NAS | Users needing high drive capacity and scalable networking | Check price of QNAP TS-673-4G 8-Bay NAS on Amazon |
The products compared
Synology 4-Bay Rackmount Expansion Unit
Best for: expanding Synology NAS storage
- Number of Bays
- 4-Bay (what this guide is about)
- Drive Bays
- 4-Bay
- Included Storage
- Diskless
- Dimensions
- 17 × 11.4 × 1.73 inches
- Weight
- 9.44 pounds
View on Amazon: Synology 4-Bay Rackmount Expansion Unit Affiliate link
The Synology RX418 is a 4-bay diskless expansion unit designed to increase storage capacity for existing Synology NAS systems. It measures 17 x 11.4 x 1.73 inches and weighs 9.44 pounds. You can manage it through Synology DiskStation Manager. The unit supports online volume expansion and includes an energy-saving deep sleep mode. It fits 2-post racks.
Pros
- 4-bay capacity for additional drives
- Plug-and-play design for seamless upgrades
- Supports online volume expansion
- Energy-saving deep sleep mode
Cons
- Diskless design requires separate drive purchase
- Requires existing Synology NAS system
- Limited to Synology DSM management
Good fit if
- You need more storage for a Synology NAS
- You want plug-and-play expansion
- You manage storage via DSM
Skip if
- You need a standalone NAS
- You want pre-installed drives
- You use non-Synology systems
Verdict: Synology RX418 4-Bay Expansion Unit is a practical add-on for Synology users needing more space. It fits those expanding existing setups via DSM.
QNAP TS-673-4G 8-Bay NAS
Best for: Users needing high drive capacity and scalable networking
- Number of Bays
- 8-Bay (what this guide is about)
- Drive Bays
- 6 Bay
- Network Connectivity
- 4x GbE LAN
- RAM Capacity
- 4GB DDR4
- M.2 NVMe Slots
- 2 slots
- Processor Cores
- Quad-Core
View on Amazon: QNAP TS-673-4G 8-Bay NAS Affiliate link
This 8-bay NAS features an AMD quad-core processor and 4GB of RAM. It includes four 1GbE ports and supports optional 10GbE expansion via PCIe. Dual M.2 slots allow for SSD caching or storage pools. The unit supports virtualization, containerized apps, and 4K video transcoding with a dedicated graphics card. It suits users needing high capacity and scalable storage for centralized backup and sharing.
Pros
- Eight drive bays for large storage capacity
- Four 1GbE LAN ports for network connectivity
- Dual M.2 slots for SSD caching or storage
- Supports 10GbE expansion via PCIe cards
- Quad-core AMD processor for multitasking
Cons
- Base model includes only 4GB RAM
- Standard network ports are limited to 1GbE
- Requires separate PCIe cards for 10GbE speeds
Good fit if
- You need extensive storage for many drives
- You want to expand network speed later
- You require support for virtualization or apps
Skip if
- You need high-speed 10GbE networking out of the box
- You prefer a compact single-bay device
- You require more than 4GB of RAM without upgrades
Verdict: QNAP TS-673-4G 8-Bay NAS is a robust solution for users needing high drive capacity and scalable networking. It fits those who plan to add 10GbE expansion or require dedicated resources for virtualization and media transcoding.
Specifications side by side
| Spec | Synology 4-Bay Rackmount Expansion Unit | QNAP TS-673-4G 8-Bay NAS |
|---|---|---|
| Drive Bays | 4-Bay | 6 Bay |
| Network Connectivity | not stated | 4x GbE LAN |
| RAM Capacity | not stated | 4GB DDR4 |
| M.2 NVMe Slots | not stated | 2 slots |
| Included Storage | Diskless | not stated |
| Number of Bays | 4-Bay | 8-Bay |
| Processor Cores | not stated | Quad-Core |
| Dimensions | 17 × 11.4 × 1.73 inches | 11 × 10.4 × 7.41 inches |
| Weight | 9.44 pounds | 12.3 pounds |
| Size | 44 mm x 480 mm x 325 mm | 4GB RAM |
| Color | black | Black |
| Model | RX418 | TS-673-4G-US |
Frequently asked questions
Can a 4-Bay NAS replace a standalone 8-Bay system?
No. The Synology RX418 is an expansion unit, not a standalone device. It requires an existing Synology NAS to function. It adds four bays to your current setup. The QNAP TS-673-4G operates independently. It includes its own processor and RAM. Choose the QNAP if you need a single, self-contained unit.
Does the 8-Bay NAS support faster networking?
Yes. The QNAP TS-673-4G includes 1GbE connectivity. The product data notes it fits users who plan to add 10GbE expansion. This allows you to upgrade bandwidth later. The Synology RX418 has no network ports listed. It connects only to your main NAS. Network speed depends on your primary device.
Which device is better for virtualization?
The QNAP TS-673-4G is better. It features a Quad-Core processor and 4GB of RAM. The verdict states it provides dedicated resources for virtualization. The Synology RX418 has no processor or RAM. It relies entirely on the host NAS for processing power. You need the QNAP for independent virtualization tasks.
How much physical space does each device take?
The Synology RX418 is smaller. It measures 17 inches in length and weighs 9.44 pounds. The QNAP TS-673-4G is bulkier. It measures 11 inches in length but 7.41 inches in height. It weighs 12.3 pounds. The Synology unit is designed for rackmount expansion. The QNAP is a standalone tower. Consider your rack or desk space.
Can I add M.2 SSDs to the 4-Bay unit?
No. The Synology RX418 offers only four standard drive bays. The data does not list M.2 slots for this unit. The QNAP TS-673-4G includes two M.2 NVMe slots. It also has six standard drive bays. If you need NVMe caching or storage, you must choose the 8-Bay QNAP model.
Is the 4-Bay unit compatible with all NAS brands?
No. The Synology RX418 is designed for Synology users. It integrates via DSM, Synology’s operating system. It expands existing Synology setups. The QNAP TS-673-4G is a standalone QNAP device. It does not require another NAS to work. Brand compatibility is strict for the expansion unit.