The catch
Synology DiskStation DS725+
No more than two onboard M.2 sockets
Side by side
Synology DS725+ vs ASUSTOR AS5402T Compared: ASUSTOR fits four NVMe drives, and Synology supports more ECC RAM
Quick verdict
ECC memory and a supported path beyond 16 GB point to the DS725+ when they matter more than SSD socket count. If the plan already needs three or four internal NVMe drives or two native 2.5GbE links, choose the AS5402T. Two SATA bays are the starting point on both, so list every drive before buying.
Before you buy
Why, and what it costs you
The socket question is settled by three NVMe drives
With a plan of three internal NVMe drives, one AS5402T slot stays spare, while DS725+ comes up one socket short.
Where this comes from
Three separate internal NVMe devices make up the drive plan. Four sockets on AS5402T leave one spare, and the two sockets on DS725+ leave a shortfall of one device.
The catch
ASUSTOR Nimbustor 2 Gen2
The limit for supported RAM is 16 GB
Synology DiskStation DS725+
- Why pick it
- Rely on documented ECC memory and a 32 GB ceiling
- Bring in a supported DX525 later should more SATA bays become necessary
- The catch
- No more than two onboard M.2 sockets
ASUSTOR Nimbustor 2 Gen2
- Why pick it
- Fit as many as four supported internal NVMe drives
- Run two separate 2.5GbE network paths with no network adapter needed
- The catch
- The limit for supported RAM is 16 GB
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What this page compares
When a two-bay NAS needs ECC memory, four NVMe drives or two separate multi-gigabit network connections, here is how DS725+ and AS5402T compare.
ECC memory and a supported path beyond 16 GB point to the DS725+ when they matter more than SSD socket count. If the plan already needs three or four internal NVMe drives or two native 2.5GbE links, choose the AS5402T. Two SATA bays are the starting point on both, so list every drive before buying.
Which one fits
Pick the situations that sound like you
The parts list already includes three or four internal NVMe drives
That all-internal SSD arrangement is ruled out on DS725+ by the socket count.
- Synology DiskStation DS725+
- Not suitable
- ASUSTOR Nimbustor 2 Gen2
- Better fit
A documented 24 GB RAM requirement applies to the applications
Against 16 GB for AS5402T, Synology lists a 32 GB maximum.
- Synology DiskStation DS725+
- Better fit
- ASUSTOR Nimbustor 2 Gen2
- Not suitable
Each of two separate network segments needs a native 2.5GbE port
Two native ports at that rate are found only on AS5402T.
- Synology DiskStation DS725+
- Caution
- ASUSTOR Nimbustor 2 Gen2
- Better fit
Two hard drives with one ordinary network connection do the job
In a simple two-drive file server, the large differences may go unused.
- Synology DiskStation DS725+
- Good
- ASUSTOR Nimbustor 2 Gen2
- Good
In practice
Differences you will notice
The socket question is settled by three NVMe drives
With a plan of three internal NVMe drives, one AS5402T slot stays spare, while DS725+ comes up one socket short.
How we worked this out
Three separate internal NVMe devices make up the drive plan. Four sockets on AS5402T leave one spare, and the two sockets on DS725+ leave a shortfall of one device.
Aiming for 24 GB of memory crosses one supported ceiling
A 24 GB plan is over the 16 GB maximum of AS5402T, whereas DS725+ supports up to 32 GB.
How we worked this out
The workload target is a minimum of 24 GB, and no claim is made that an exact 24 GB module combination is supported. DS725+ allows a supported 32 GB configuration, and AS5402T lists a 16 GB ceiling.
Two network cables are not two equivalent links
Two native 2.5GbE ports come with AS5402T. DS725+ has one 2.5GbE port next to a Gigabit port.
How we worked this out
Each physical Ethernet connector is compared on its own, with two 2.5GbE sockets on AS5402T against one 2.5GbE and one Gigabit socket on DS725+. No aggregation gain is assumed.
Option A
Synology, DS725+
Synology DiskStation DS725+
This two-bay DSM system has ECC memory and two NVMe sockets, with a separate DX525 as the expansion path.
- Best for
- Rely on documented ECC memory and a 32 GB ceiling
Facts we checked
- SATA bays: 2
- NVMe slots in M.2: 2
- Memory installed: 4 GB ECC
- Largest supported RAM: 32 GB
Option B
ASUSTOR, AS5402T
ASUSTOR Nimbustor 2 Gen2
A 2-bay chassis whose fastest documented network path is 2.5 Gbps.
- Best for
- Fit as many as four supported internal NVMe drives
Facts we checked
- SATA bays: 2
- NVMe slots in M.2: 4
- Memory installed: 4 GB DDR4
- Largest supported RAM: 16 GB
Spec by spec
Where they really differ
| Spec | Synology DiskStation DS725+ | ASUSTOR Nimbustor 2 Gen2 | In practice |
|---|---|---|---|
| SATA bays | 2 | 2 | A four-drive SATA array cannot be created inside the base enclosure of either. |
| M.2 NVMe slots | 2 | 4 | The Synology socket count falls short of a three-SSD internal plan. |
| Installed memory | 4 GB ECC | 4 GB DDR4 | The documented memory type differs even though installed capacity matches. |
| Supported RAM maximum | 32 GB | 16 GB | A supported hardware limit is crossed by a workload that requires more than 16 GB. |
| Native network ports | One 2.5GbE and one 1GbE | Two 2.5GbE | Only on AS5402T is the second connection multi-gigabit. |
Trade-offs
What each pick costs you
With Synology DiskStation DS725+
- Gigabit is the limit for the second native network port
With ASUSTOR Nimbustor 2 Gen2
- SATA bay count is not raised by the four-SSD socket advantage
Change of plan
When the answer changes
Three internal NVMe drives are required by the plan
Go with ASUSTOR Nimbustor 2 Gen2. The physical count is satisfied by four M.2 sockets.
Both system-level ECC and supported RAM above 16 GB are required
Go with Synology DiskStation DS725+. ECC memory and a 32 GB maximum are documented for DS725+.
Four SATA drives have to fit inside the base enclosure for the project
Neither model fits. Two SATA bays are on each base unit.
Decision guide
How to decide
The socket question is settled by three NVMe drives
Count the physical SSDs apart from the roles they play. Cache, an application pool and a mirrored pool can use up sockets fast. The AS5402T supplies four sockets against two in the DS725+. Before assuming all proposed roles can coexist, check the supported pool and cache configurations.
Aiming for 24 GB of memory crosses one supported ceiling
Begin with the memory your intended applications and guest systems require. Both selected configurations start at 4 GB. A workload that needs at least 24 GB would call for a supported 32 GB configuration on Synology, and it lies beyond the ASUSTOR 16 GB limit. Extra RAM alone does not establish application compatibility or performance.
Two network cables are not two equivalent links
It matters when a NAS serves two independently connected network segments, because the slower second Synology port can become the constraint on that segment. Neither arrangement promises one file transfer the sum of both port rates.
What this page can’t tell you
- There is no matched file-transfer or application benchmark available
- Having NVMe sockets does not promise unrestricted storage-pool support
By the numbers
What the data shows
What we found across the NAS devices we compare, plus the checked facts behind each finding.
Show the facts and the math
| Product | Needs it meets | Facts we checked | Sources |
|---|---|---|---|
| Synology DiskStation DS725+ |
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| ASUSTOR Nimbustor 2 Gen2 |
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Ready to buy
See today’s price and what owners say
Open either model on Amazon for the current price, customer reviews and delivery options.
Synology DiskStation DS725+
Rely on documented ECC memory and a 32 GB ceiling
See price & reviews on AmazonASUSTOR Nimbustor 2 Gen2
Fit as many as four supported internal NVMe drives
See price & reviews on AmazonEach link opens in a new tab.
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