Ten-gigabit gets the attention. Two-and-a-half-gigabit quietly turned up on nearly every motherboard and mini PC sold in the last few years, and most people have it without knowing.
That second fact reframes the question. This is not “which network should I build” — it is “do I need to upgrade past the network I already own?“
What each tier actually delivers
Line rate is not throughput. After protocol overhead, the practical figures are:
| Link | Line rate | Realistic throughput | Time to move 42 GB |
|---|---|---|---|
| 1 GbE | 1,000 Mbps | ~113 MB/s | 6 min 12 s |
| 2.5 GbE | 2,500 Mbps | ~280 MB/s | 2 min 30 s |
| 5 GbE | 5,000 Mbps | ~560 MB/s | 1 min 15 s |
| 10 GbE | 10,000 Mbps | ~1,100 MB/s | 38 s |
Forty-two gigabytes is a 70-billion-parameter model at 4-bit quantisation — a useful yardstick for this audience, and a file size that makes the differences concrete.
The step from gigabit to 2.5 is the one that changes behaviour. Six minutes is long enough that you go and do something else; two and a half is long enough to be mildly annoying. Forty seconds is short enough that you wait.
The question that decides it: what is at the other end?
Network speed only matters if the storage can produce data that fast. This is where most 10-gigabit disappointment comes from.
| Storage | Realistic sequential read | Saturates… |
|---|---|---|
| Single 7,200 rpm hard disk | 150–250 MB/s | 2.5 GbE, roughly |
| Four-drive HDD array | 300–500 MB/s | 2.5 GbE comfortably; not 10 |
| SATA SSD | ~550 MB/s | 5 GbE |
| NVMe PCIe 3.0 | ~3,500 MB/s | 10 GbE easily |
| NVMe PCIe 4.0 | 5,000–7,000 MB/s | 10 GbE with room to spare |
Read those two tables together and the answer falls out.
If your NAS is spinning disks, 2.5 GbE captures most of what the array can give you. A four-drive HDD array producing 400 MB/s against a 2.5-gigabit link that carries 280 is leaving something on the table — but upgrading to 10 gigabit only recovers that 120 MB/s, not the 800 the link is theoretically capable of.
If your NAS has NVMe storage or an SSD cache tier, 10 GbE is the only tier that keeps up. This is the case where the upgrade genuinely pays for itself.
What the upgrade actually costs
The switch is the visible cost and rarely the largest one.
Getting to 2.5 gigabit:
- A switch. Small unmanaged 2.5-gigabit switches are inexpensive and fanless.
- Adapters: usually none. Most motherboards and mini PCs sold since about 2022 include 2.5 GbE. Check before buying anything.
- Cabling: none. 2.5GBASE-T is specified to run over Cat5e at full distance.
Getting to 10 gigabit:
- A switch, at a substantially higher price per port than 2.5.
- An adapter for every machine. Very few consumer motherboards include 10 gigabit. This is the cost people forget, and it multiplies by the number of machines. See Best 10GbE Network Adapters.
- Cabling, possibly. 10GBASE-T needs Cat6 to 55 m or Cat6a to 100 m. If your house is wired with Cat5e, some runs may not carry it reliably.
- DAC cables or transceivers, if you go the SFP+ route.
The gap between “buy one switch” and “buy one switch, four network cards, and possibly re-run cable” is what makes 2.5 gigabit such good value, not the switch price.
Cabling is the sleeper advantage
This deserves its own heading because it changes the answer for anyone in an older house.
2.5GBASE-T was designed specifically to run over existing Cat5e, at the full 100-metre distance. That was the entire point of the standard — it exists so that buildings already wired for gigabit could go faster without new cable.
10GBASE-T was not. It needs Cat6 for 55 metres, or Cat6a for the full 100. Cat5e will sometimes carry 10 gigabit over short runs, and “sometimes” is not a basis for a network you rely on.
If the cable is already in your walls and pulling new runs means lifting floors, 2.5 gigabit is not a compromise. It is the only sensible option.
Power, over a year
The running cost difference is larger than most people assume, because it applies to the adapters as well as the switch.
Take a modest lab: a switch and three connected machines.
| 2.5 GbE | 10GBASE-T | |
|---|---|---|
| Switch | ~5 W | ~22 W |
| Adapters, three machines | ~0 W (onboard) | ~36 W (12 W each) |
| Total continuous | ~5 W | ~58 W |
| Per year | 44 kWh | 508 kWh |
| At $0.16/kWh | $7 | $81 |
| At £0.25/kWh | £11 | £127 |
Choosing SFP+ instead of copper roughly halves the 10-gigabit figure, which is one more reason fanless SFP+ switches dominate quiet labs.
It is not a decisive argument on its own. It is worth knowing that the faster network costs something every day, not just once.
When 2.5 gigabit is genuinely enough
- Your NAS is spinning disks. The array cannot fill more than this anyway.
- You stream media, even 4K. A high-bitrate 4K remux is around 100 Mbps. Gigabit was already ample; 2.5 is generous.
- Backups run overnight. Nobody is watching.
- The house is wired with Cat5e and re-cabling is not happening.
- You want the upgrade to be one purchase. A switch, and everything else already has the ports.
When 10 gigabit is genuinely necessary
- Your NAS has NVMe storage or an SSD cache tier. This is the clearest case.
- You edit video from network storage. Scrubbing a timeline over the network is exactly what this is for.
- You pull large model libraries repeatedly. Forty seconds against two and a half minutes changes whether network storage is somewhere you keep things or somewhere you avoid.
- You migrate virtual machines between hosts, or run distributed storage such as Ceph — which wants 10 gigabit as a baseline, not a luxury.
- Two workstations move large files directly. No spinning disk in the path, so nothing else is the bottleneck.
The awkward middle: 5 gigabit
Worth mentioning because it exists and because most people should skip it.
5GBASE-T sits between the two on every axis, and the ecosystem never really formed around it — switches are uncommon and not obviously cheaper than 10-gigabit ones. Where it genuinely appears is USB adapters, because USB 3.0’s 5 Gbps of raw bandwidth is a natural ceiling for a dongle.
So the practical use for 5 gigabit is a laptop or a slotless mini PC that needs to be faster than 2.5 and cannot take a card. As a network tier to build around, it is a tier to skip.
One caveat worth knowing about 2.5-gigabit hardware
Early Intel I225-V controllers — widely used on motherboards from around 2020 — had a hardware fault that caused intermittent link drops. Intel fixed it in later silicon revisions and in the successor I226-V.
If you have a machine of that vintage dropping its 2.5-gigabit link, that is very likely the cause rather than your cabling or your switch. Realtek’s RTL8125, used on many boards and mini PCs, does not share the problem.
The winner, by scenario
| Your situation | Buy | Why |
|---|---|---|
| HDD-based NAS | 2.5 GbE | The array cannot fill more than this |
| NVMe or SSD-cached NAS | 10 GbE | The only tier that keeps up with the storage |
| House wired with Cat5e | 2.5 GbE | 10GBASE-T is not specified for it, and “usually works” is not a network |
| Media streaming and backups | 2.5 GbE | Generous for the job, by a wide margin |
| Video editing from the network | 10 GbE | Scrubbing a timeline needs the bandwidth |
| Moving large model files often | 10 GbE | 38 seconds against 2 min 30 changes the habit |
| Proxmox cluster with Ceph | 10 GbE | Distributed storage treats this as the floor |
| Machines already have 2.5 GbE onboard | 2.5 GbE first | One switch, no adapters, no cabling. Upgrade later if it binds |
| A quiet room, and cost matters | 2.5 GbE | Roughly a twelfth of the continuous power draw |
The verdict
For most homes, 2.5 gigabit is the correct answer, and the reason is that it is nearly free. The ports are already on your machines, the cable is already in your walls, and the switch costs a fraction of a 10-gigabit one. It is 2.5 times faster than what you have for the price of one purchase.
Ten gigabit is worth it when your storage can fill it — an NVMe-backed NAS, an SSD cache tier, or direct workstation-to-workstation transfers. In that situation it is transformative, and network storage stops being a place you avoid.
The mistake to avoid is buying 10 gigabit for a network of hard disks. You will spend several times as much, add close to 50 W of continuous draw, possibly re-cable, and gain perhaps 30% on real transfers because the array was always the bottleneck.
If you are unsure, start at 2.5. It is cheap enough to be a low-risk decision, it uses hardware you already own, and if it turns out to bind you have lost very little. Ten gigabit will still be there, and cheaper, when your storage is ready for it.
Common questions
Is 2.5GbE enough for a NAS?
If the NAS uses spinning disks, yes — comfortably. A four-drive array produces 300–500 MB/s and 2.5 GbE carries about 280, so you capture most of what the array can give. If the NAS is NVMe-backed or has an SSD cache tier, it will outrun 2.5 gigabit and 10 is the right tier.
Does 2.5GbE work over Cat5e?
Yes, and that is the entire reason the standard exists — it is specified for Cat5e at the full 100 metres. 10GBASE-T is not: it needs Cat6 for 55 metres or Cat6a for 100. Cat5e will sometimes carry 10 gigabit over short runs, which is not a basis for a network you rely on.
Do I already have 2.5GbE?
Probably, if the machine was made after about 2022. Most AM5 and LGA1700 motherboards and nearly every recent mini PC include it, usually via a Realtek RTL8125 or an Intel I225/I226. Check before buying adapters — the upgrade may be a switch and nothing else.
How much faster is 10GbE in practice?
About four times, when nothing else is the bottleneck: roughly 1,100 MB/s against 280. A 42 GB file takes 38 seconds instead of two and a half minutes. Whether you see that depends entirely on whether the storage at each end can produce data that fast.
Should I skip 2.5 and go straight to 10?
Only if your storage is already flash-backed. Otherwise you are paying several times as much, adding around 50 W of continuous draw, possibly re-cabling, and gaining perhaps 30% on real transfers — because the disk array was always the limit.
What about 5GbE?
A tier to skip as a network design. Switches are uncommon and not obviously cheaper than 10-gigabit ones. It does have one genuine use: USB adapters, where USB 3.0’s 5 Gbps of raw bandwidth makes it the natural ceiling for a laptop or a slotless mini PC.
My 2.5GbE link keeps dropping. Why?
If the machine is from around 2020, it is very likely an early Intel I225-V controller, which had a hardware fault causing intermittent link drops. Intel fixed it in later revisions and in the I226-V. It is far more often that than your cabling or your switch.
Continue your research
- Best 10GbE Switches for Homelabs — if you have decided on the faster tier
- Best 10GbE Network Adapters — the cost people forget to budget
- Best Mini PCs for Homelabs — nodes with 2.5 and 10-gigabit built in
- Best NVMe SSDs for AI Workloads — the storage that decides which tier you need