MikroTik CRS312-4C+8XG-RM 12-Port 10GbE Switch — 8x 10G RJ45 + 4x SFP+/RJ45 Combo, Dual PSU, Refurbished
Warranty: Lifetime
12 ports of 10G over the copper you already have — with four SFP+ combo ports for fiber or DAC
MikroTik CRS312-4C+8XG-RM — 8x 10GBASE-T + 4x 10G combo (SFP+ or RJ45), 1U, dual power
→ Combo ports are either/or. Each of the four combo ports has an SFP+ cage and an RJ45 jack, and only one can be active at a time. If both are plugged in, the SFP+ side wins unless you choose otherwise in RouterOS.
Part Number: CRS312-4C+8XG-RM
Description: MikroTik Cloud Router Switch, 8x 1/2.5/5/10G RJ45, 4x 10G combo (SFP+ or 10G RJ45), 1x 10/100 management, dual AC power, 1U rackmount
The CRS312-4C+8XG-RM was MikroTik's first switch with 10G RJ45 ports. It is the straightforward way to move a rack, studio or office core from 1 Gigabit to 10 Gigabit over existing copper, while keeping up to four SFP+ ports for fiber or DAC uplinks.
The eight RJ45 ports also negotiate 1, 2.5 and 5G, so older NICs and multi-gig access points keep working. It dual-boots RouterOS (license level 5) or the simpler SwOS, and has redundant power supplies.
Which One Do I Need?
| If you need | This switch? |
|---|---|
| 10GBASE-T to servers, NAS or workstations over Cat6A | Yes — 8 RJ45 ports, plus the 4 combo ports in RJ45 mode for up to 12 |
| SFP+ fiber or DAC uplinks | Yes — up to 4, using the combo ports in SFP+ mode |
| PoE to access points or cameras | No — this switch does not supply PoE |
| 25G or 100G uplinks | No — every port tops out at 10G |
| Layer 3 routing on the switch | Yes, under RouterOS; SwOS is switching only |
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | CRS312-4C+8XG-RM |
| RJ45 ports | 8x 1/2.5/5/10GBASE-T |
| Combo ports | 4x 10G, each SFP+ or 10G RJ45, one at a time |
| Management port | 1x 10/100 Ethernet |
| Non-blocking throughput | 120 Gbps |
| Switching capacity | 240 Gbps |
| Forwarding rate | 178 Mpps |
| Switch chip | Marvell 98DX8212 |
| CPU | QCA9531, 650MHz, single core |
| RAM / storage | 64MB RAM / 16MB flash per the original brochure; MikroTik's current spec lists 128MB / 32MB |
| Operating system | RouterOS (license level 5) or SwOS, dual boot |
| Power | 2x AC inputs, 100–240V, redundant · 60W max |
| Cooling | 4 fans |
| Other ports | USB Type-A, RJ45 serial console |
| Dimensions | 443 x 183 x 44mm, 1U rackmount |
| Tested ambient temperature | -30°C to 70°C |
| Certifications | CE, EAC, RoHS |
| Condition | Refurbished |
| Warranty | Lifetime, backed by Resilient Tec |
Source: MikroTik CRS312-4C+8XG-RM product page, brochure and quick guide.
Note on Throughput: 120 Gbps or 240 Gbps?
MikroTik quotes 120 Gbps of non-blocking throughput and 240 Gbps of switching capacity. They describe the same thing: 12 ports x 10G is 120 Gbps in one direction and 240 Gbps counting both directions. Every port can run at line rate at the same time.
Good to Know
- 10GBASE-T needs the right cable. Plan on Cat6A or better for full 10G at distance on the RJ45 ports.
- Combo ports are either/or. Four combo ports give you four connections, not eight. In RouterOS you can pick which side of each combo is active.
- RouterOS or SwOS. RouterOS gives full routing and switching features; SwOS is a lighter switch-only OS. You choose which one boots.
- Combo SFP+ ports take standard 10G optics and DACs. MikroTik publishes an SFP module compatibility table if you want to check a specific part.
Quick Checklist — Is This the Right Switch?
You want 10G to up to 12 devices in 1U. Most of your runs are copper (Cat6A), with up to four fiber or DAC links. You do not need PoE or anything faster than 10G. You want redundant power and the option of routing under RouterOS.
Availability
Refurbished and shipped from Resilient Tec in Knoxville, TN · Free standard shipping on US orders.
Buying several, or pairing this with NICs and cabling? Tell us what you are connecting and we will quote it together. Request a quote →
Warranty: lifetime, backed by Resilient Tec — not a manufacturer term. On switches that means advance replacement when we have one in stock, otherwise repair or replacement with an equivalent unit, from a named seller in the US.
You Might Also Need
- Cat 6A UTP slim patch cable — for the 10GBASE-T ports
- OM4 LC-to-LC fiber patch cable — for SR optics in the combo ports
- DAC cables and SFP+ transceivers for the four combo ports
- Ethernet Cabling Guide — choosing a cable category for 10G copper
- Product guides — structured cabling, switches and the rest of the rack
Related Guides
DAC vs AOC vs AEC: Which Cable Goes Where in an AI Rack? (2026 Buyer's Guide)
12 ports of 10G over the copper you already have — with four SFP+ combo ports for fiber or DAC
MikroTik CRS312-4C+8XG-RM — 8x 10GBASE-T + 4x 10G combo (SFP+ or RJ45), 1U, dual power
→ Combo ports are either/or. Each of the four combo ports has an SFP+ cage and an RJ45 jack, and only one can be active at a time. If both are plugged in, the SFP+ side wins unless you choose otherwise in RouterOS.
Part Number: CRS312-4C+8XG-RM
Description: MikroTik Cloud Router Switch, 8x 1/2.5/5/10G RJ45, 4x 10G combo (SFP+ or 10G RJ45), 1x 10/100 management, dual AC power, 1U rackmount
The CRS312-4C+8XG-RM was MikroTik's first switch with 10G RJ45 ports. It is the straightforward way to move a rack, studio or office core from 1 Gigabit to 10 Gigabit over existing copper, while keeping up to four SFP+ ports for fiber or DAC uplinks.
The eight RJ45 ports also negotiate 1, 2.5 and 5G, so older NICs and multi-gig access points keep working. It dual-boots RouterOS (license level 5) or the simpler SwOS, and has redundant power supplies.
Which One Do I Need?
| If you need | This switch? |
|---|---|
| 10GBASE-T to servers, NAS or workstations over Cat6A | Yes — 8 RJ45 ports, plus the 4 combo ports in RJ45 mode for up to 12 |
| SFP+ fiber or DAC uplinks | Yes — up to 4, using the combo ports in SFP+ mode |
| PoE to access points or cameras | No — this switch does not supply PoE |
| 25G or 100G uplinks | No — every port tops out at 10G |
| Layer 3 routing on the switch | Yes, under RouterOS; SwOS is switching only |
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | CRS312-4C+8XG-RM |
| RJ45 ports | 8x 1/2.5/5/10GBASE-T |
| Combo ports | 4x 10G, each SFP+ or 10G RJ45, one at a time |
| Management port | 1x 10/100 Ethernet |
| Non-blocking throughput | 120 Gbps |
| Switching capacity | 240 Gbps |
| Forwarding rate | 178 Mpps |
| Switch chip | Marvell 98DX8212 |
| CPU | QCA9531, 650MHz, single core |
| RAM / storage | 64MB RAM / 16MB flash per the original brochure; MikroTik's current spec lists 128MB / 32MB |
| Operating system | RouterOS (license level 5) or SwOS, dual boot |
| Power | 2x AC inputs, 100–240V, redundant · 60W max |
| Cooling | 4 fans |
| Other ports | USB Type-A, RJ45 serial console |
| Dimensions | 443 x 183 x 44mm, 1U rackmount |
| Tested ambient temperature | -30°C to 70°C |
| Certifications | CE, EAC, RoHS |
| Condition | Refurbished |
| Warranty | Lifetime, backed by Resilient Tec |
Source: MikroTik CRS312-4C+8XG-RM product page, brochure and quick guide.
Note on Throughput: 120 Gbps or 240 Gbps?
MikroTik quotes 120 Gbps of non-blocking throughput and 240 Gbps of switching capacity. They describe the same thing: 12 ports x 10G is 120 Gbps in one direction and 240 Gbps counting both directions. Every port can run at line rate at the same time.
Good to Know
- 10GBASE-T needs the right cable. Plan on Cat6A or better for full 10G at distance on the RJ45 ports.
- Combo ports are either/or. Four combo ports give you four connections, not eight. In RouterOS you can pick which side of each combo is active.
- RouterOS or SwOS. RouterOS gives full routing and switching features; SwOS is a lighter switch-only OS. You choose which one boots.
- Combo SFP+ ports take standard 10G optics and DACs. MikroTik publishes an SFP module compatibility table if you want to check a specific part.
Quick Checklist — Is This the Right Switch?
You want 10G to up to 12 devices in 1U. Most of your runs are copper (Cat6A), with up to four fiber or DAC links. You do not need PoE or anything faster than 10G. You want redundant power and the option of routing under RouterOS.
Availability
Refurbished and shipped from Resilient Tec in Knoxville, TN · Free standard shipping on US orders.
Buying several, or pairing this with NICs and cabling? Tell us what you are connecting and we will quote it together. Request a quote →
Warranty: lifetime, backed by Resilient Tec — not a manufacturer term. On switches that means advance replacement when we have one in stock, otherwise repair or replacement with an equivalent unit, from a named seller in the US.
You Might Also Need
- Cat 6A UTP slim patch cable — for the 10GBASE-T ports
- OM4 LC-to-LC fiber patch cable — for SR optics in the combo ports
- DAC cables and SFP+ transceivers for the four combo ports
- Ethernet Cabling Guide — choosing a cable category for 10G copper
- Product guides — structured cabling, switches and the rest of the rack
Related Guides
DAC vs AOC vs AEC: Which Cable Goes Where in an AI Rack? (2026 Buyer's Guide)