How loud is a Synology NAS?
Between 14.6 and 25 dB(A) idle for a current DiskStation, depending on the model and the drives Synology fitted for the test. RackStation rackmount units list 22.8 to 56.2 dB(A).
The test room is the constant. Synology describes it as 16.49 to 17.51 dB(A) of background, 24.25 to 25.75˚C and 58.2 to 61.8% humidity, with a pair of GRAS 40AE microphones a meter in front of and behind the unit. The drive and the chassis are what change. Noise is checked only at idle, too, so a NAS copying files, scrubbing a volume or spinning up drives will be louder than its row says, and there is no working figure to show by how much.
With Synology hard drives, the DS725+ leads
Eight current desktop lines carry the note "fully installed with Synology SATA HDDs and in an idle state", twelve model numbers once the neo+ versions are counted. The DS725+ is lowest at 17.9 dB(A).
| dB(A) | Models | Bays | Fans |
|---|
| 17.9 | DS725+ and DS725neo+ | 2 | One 92 mm |
| 19.0 | DS124 | 1 | One 60 mm |
| 19.6 | DS225+ | 2 | One 92 mm |
| 20.5 | DS925+ and DS925neo+ | 4 | Two 92 mm |
| 22 | DS224+ | 2 | One 92 mm |
| 22.60 | DS1525+ and DS1525neo+ | 5 | Two 92 mm |
| 23.6 | DS1823xs+ | 8 | Two 120 mm |
| 23.8 | DS1825+ and DS1825neo+ | 8 | Two 120 mm |
The note does not say which Synology drive model went in, so two buyers fitting different drives will hear different machines. Within this table the ranking holds, because the wording, room and microphones are identical.
Bay count changes less than you might guess. Going from the two bay DS725+ to the eight bay DS1825+ adds 5.9 dB(A), with six more drives and two larger fans.
The older note reads "Fully loaded with Seagate 2TB ST2000VN000 hard drive(s) in the idle state", and four current DiskStations carry it. The two bay DS223j is lowest, at 18.2 dB(A); the four bay DS423 lists 20.6, and the twelve bay DS2422+ and DS3622xs+ both list 25.
This note names the drive and says every bay held one, which is more than the newer wording offers. It still uses a different drive from the table above. A DS223j at 18.2 should not be read as louder than a DS725+ at 17.9 by a measured margin.
The two twelve bay models tie despite different processors, an AMD Ryzen V1500B in the DS2422+ and an Intel Xeon D-1531 in the DS3622xs+. Both use two 120 mm fans.
The DS223 and DS425+ were tested with SSDs
The DS223's 14.6 dB(A) and the DS425+'s 21.6 were both taken with Synology SATA SSDs, which make no spindle or seek noise. They describe fans and chassis more than a working storage box, and they compare only with each other.
The DS223's 14.6 also sits below the background range given in the same note. How a number under the room floor was reached is not explained. Anyone filling a DS223 with spinning drives should read the DS223j or DS725+ rows instead, since their test conditions are closer to what that box will become.
RackStations run from 22.8 to 56.2 dB(A)
The same three notes apply, from 22.8 dB(A) for the RS1226RP+ to 56.2 for the RS2423RP+II. Rack units hold more drives behind smaller fans, 40 to 80 mm on the models we catalogued.
| Test note | Model | Form, bays | dB(A) |
|---|
| Synology hard drives | RS1226RP+ | 2U, eight | 22.8 |
| Synology hard drives | RS826+ | 1U, four | 26.5 |
| Synology hard drives | RS422+ | 1U, four | 28.5 |
| Synology hard drives | RS3626xs | | 38.8 |
| Synology hard drives | RS826RP+ | 1U, four | 41.2 |
| Seagate 2TB | RS1221+ | 2U, eight | 37.8 |
| Seagate 2TB | RS4021xs+ | | 44.7 |
| Seagate 2TB | RS3618xs, RS3621xs+ and RS3621RPxs | | 50.2 |
| Seagate 2TB | RS1221RP+ | 2U, eight | 53.5 |
| SSDs | RS1226+ | 2U, eight | 23.3 |
| SSDs | RS6426xs+ | | 42.2 |
| SSDs | RS4826xs+ | | 46.3 |
| SSDs | RS2825RP+ | | 49.6 |
| SSDs | RS2423+ | | 52.3 |
| SSDs | RS1626xs+ | | 52.6 |
| SSDs | RS11626xs+ | | 52.9 |
| SSDs | RS2423RP+II | | 56.2 |
Redundant power costs decibels where both twins share a note. The RS826RP+ lists 14.7 dB(A) more than the RS826+, and the RS1221RP+ 15.7 more than the RS1221+. The RS1226 pair cannot be compared that way, because the RP+ was tested with hard drives and the plain RS1226+ with SSDs.
Synology also sells FS flash, SA scale-out and HD high density rack systems, which this page does not rank.
Why is a Synology NAS noisy?
Mostly the drives and the fan mode. The published figures are idle only, so they leave out drives seeking, spinning up and working through scheduled tasks.
The fan setting is the part you control. Cool Mode runs the fan "at a higher speed, keeping your Synology NAS cooler, but emitting more noise", according to Synology's fan speed mode article, while Quiet Mode runs it "at a lower speed, emitting less noise, but the temperature of your Synology NAS may rise." No spec page says which mode produced its Noise Level figure. The same article adds that installing extra network cards disables some fan options "to ensure optimal heat dissipation", so a box with an added card may lose the quieter settings.
Drives are the other half.
Our quietest hard drives guide ranks drives by their makers' idle and seek figures, and pairing a quiet chassis with loud drives undoes most of what the Noise Level row promises.
Which fan speed mode is quietest on a Synology?
Low-power Mode, where it exists, because the fan stops once the unit has cooled. Elsewhere, Quiet Mode is the lowest setting.
The article describes Low-Power Mode as running the fan slowly, and "when your Synology NAS has cooled down, the fan will stop to save power." Among current DiskStations, only the DS124 and DS223j spec pages list it; the rest list Full-Speed, Cool and Quiet.
The setting lives at Control Panel, Hardware & Power, General, Fan Speed Mode. Drive hibernation, in the same panel, lets idle drives "stop spinning to reduce power consumption", though "All hibernation modes, including deep sleep, will stop when the system is accessed."
What is the difference between a Synology neo+ and plus model?
Memory, on the four pairs Synology sells. The neo+ column reads "4 GB DDR4 non-ECC SODIMM" where the plus model lists ECC memory, and the noise figure is the same: 17.9 dB(A) for the DS725neo+, 20.5 for the DS925neo+, 22.60 for the DS1525neo+ and 23.8 for the DS1825neo+. Fans, power draw and the test note are identical in each shared table.
On Amazon on November 7, 2026, the neo+ diskless listings showed only scarce stock or a future date, so none is a pick here.
Discontinued models open the Download Center
Every current US DiskStation and RackStation spec page we opened prints a Noise Level row.
Several models people still ask about have left the US product list: the DS923+, DS423+, DS1522+, DS723+, DS1621+, DS1821+ and DS620slim. Their old US product URLs now open the Download Center instead of a spec page, and this page treats them as discontinued in the US.
