AMD Ryzen Threadripper PRO 3945WX socket: sWRX8
The AMD Ryzen Threadripper PRO 3945WX uses sWRX8, the 4094-contact LGA socket for Threadripper PRO workstations. It is a 12-core Castle Peak chip at 280 W for WRX80 boards with 8-channel DDR4 memory.
- Socket
- sWRX8
- Launched
- July 14, 2020
- Cores and threads
- 12 and 24
- Default TDP
- 280 W
- Codename
- Castle Peak
- Segment
- Workstation
- Clocks
- 4.0 / 4.3 GHz
AMD Ryzen Threadripper PRO 3945WX specifications
| Cores | 12 |
|---|---|
| Threads | 24 |
| Core architecture | Zen 2 (Castle Peak) |
| Clocks | 4.0 GHz base, up to 4.3 GHz boost |
| Cache | 64 MB L3, 6 MB L2 and 768 KB L1 |
| Default TDP | 280 W |
| Manufacturing process | TSMC 7 nm FinFET |
| Memory support | DDR4-3200 ECC, 8 channels, up to 2 TB |
| PCI Express | 128 PCIe Gen4 lanes from the CPU |
| Integrated graphics | None (discrete card required) |
| Multiplier | Locked |
| ECC memory | Supported, RDIMM with ECC |
| Package | FC-LGA4094, socket sWRX8 |
| Cooler in the box | None, 280 W workstation heatsink required |
Motherboard and chipset compatibility
AMD Ryzen Threadripper PRO 3945WX needs a motherboard with a sWRX8 socket. The table shows which chipset series accept it.
| Series | Chipsets | Support |
|---|---|---|
| WRX80 workstation | WRX80 | Works out of the box |
Board makers publish a CPU support list for every model. Check it for your exact board before buying. Chipset details for sWRX8.
sWRX8 at a glance
| Type | LGA, 4,094 contacts |
|---|---|
| Package size | 75.4 × 58.5 mm |
| Introduced | July 2020 |
| Memory | DDR4-3200 ECC UDIMM, RDIMM, LRDIMM or 3DS RDIMM, 8 channels, up to 2 TB |
| Cooler mounting holes | Large TR4-SP3 mount (sTRX4, sWRX8, TR4 and SP3 compatible) |
What the Threadripper PRO 3945WX is
The Ryzen Threadripper PRO 3945WX is the twelve core entry to the Castle Peak workstation range that AMD listed on July 14 2020 for sWRX8 boards. Its Zen 2 cores run 4.0 GHz base with boost up to 4.3 GHz across 24 threads. Cache is 64 MB of L3 with 6 MB of L2 and 768 KB of L1, and the TSMC 7 nm FinFET process supports high clocks in a workstation envelope.
Twelve cores with high base clocks suit lightly threaded workstation work that still needs PRO platform features. The 4.0 GHz base exceeds larger PRO models by a wide margin, which helps modelling and CAD where few threads set the pace. Eight DDR4 channels feed the cores with ECC, and 128 Gen4 lanes cover GPUs and NVMe.
AMD rates the chip at 280 W default TDP with locked multiplier. The sWRX8 package carries 4094 contacts in a large LGA with carrier frame, and discrete graphics are required. The 90 C maximum operating temperature guides workstation airflow with vendor qualified heatsinks.
Socket and motherboard compatibility
The 3945WX fits sWRX8 on WRX80 with 8 DDR4 channels. Consumer sTRX4 operation with 4 channels needs a non-PRO chip, so PRO planning centres on WRX80 board choice. Firmware support for Castle Peak PRO must be installed from the maker page. The LGA socket uses three Torx screws in order with the orange carrier.
WRX80 boards for twelve cores range from single GPU creator models to multi GPU designs with BMC management. Power stages still target 280 W sustained, so dual EPS and solid case airflow remain requirements even at the entry core count. Memory population with RDIMM modules follows one DIMM per channel for full bandwidth to 2 TB.
The PRO counterpart to HEDT entry is the higher clock alternative to many-core flagships. Buyers who stay under 512 GB and use one GPU save notably with twelve cores on WRX80 over larger PRO parts. The LGA, PGA and BGA: CPU package types explained guide places sWRX8 LGA handling against desktop sockets for builders new to Threadripper torque procedures.
Memory, PCIe and cooling
DDR4 to DDR4-3200 in 8 channels with ECC gives full bandwidth to 2 TB. Primary slots first per manual, with RDIMM versus UDIMM validated per board. Larger kits need board validation for LRDIMM versus 3DS RDIMM. Memory speed past 3200 MT/s helps only where the board qualifies it, since workstation stability favours validated speeds.
PCIe from the CPU gives 128 Gen4 lanes for GPUs at by 16 and Gen5-class SSD density at Gen4 speeds plus high speed networking. Chipset lanes add SATA, USB and extra slots. Cooling needs a 280 W workstation tower or liquid unit even though core count is lower, because high clocks concentrate power. No box cooler is included.
ECC joins the CPU as a lasting choice. Boards that route ECC with RDIMM correct single bit errors in long renders and compiles, which matters more than headline memory clocks for workstation stability. Population with eight matched modules beats mixed kits for bandwidth.
Upgrade paths
On WRX80 the upward path is the 16-core AMD Ryzen Threadripper PRO 3955WX or 32-core AMD Ryzen Threadripper PRO 3975WX where rendering scales, while many owners gain more from GPU or memory steps first. Filling 8 channels and adding fast NVMe help large projects without a chip swap. The twelve core chip already holds the highest base clock in PRO 3000WX, so core steps trade clock for threads.
Moving to HEDT on sTRX4 changes channels and lanes with a board change for desktop oriented builds without ECC needs. For most 3945WX owners the value order is memory to 8 channels, then GPU, then a core step on the same sWRX8 socket where jobs scale.
Used buyers check firmware first. A WRX80 board that shipped with a twelve core part in 2020 may need no update for another Castle Peak PRO, but a jump to Chagall PRO 5000WX needs a firmware update that adds the new IDs. The existing AMD Ryzen Threadripper PRO 3995WX shows the 64-core ceiling on the same socket for reference.
Frequently asked questions
What socket does the Threadripper PRO 3945WX use?
Socket sWRX8 (LGA 4094) on WRX80 with 8 DDR4 channels. It needs Castle Peak PRO firmware support and does not work in sTRX4 boards.
What memory does the 3945WX use?
DDR4-3200 ECC in 8 channels to 2 TB, with RDIMM, LRDIMM and 3DS RDIMM on most boards. One DIMM per channel gives full bandwidth.
How many cores does the 3945WX have?
Twelve cores and 24 threads at 4.0 GHz base and up to 4.3 GHz boost, with 64 MB L3 and a 280 W TDP for high clock workstation work.
Is the 3945WX good for gaming?
It runs CAD and modelling with a discrete GPU, but HEDT gaming needs are served better by fewer channel desktop parts. High base clocks help interactive work, while board cost and 280 W cooling exceed gaming needs.
Sources and verification
- AMD Ryzen Threadripper PRO 3945WX specifications (AMD)
- Socket sWRX8 - 4094 contacts and WRX80 (Wikipedia)
- Zen 2 Castle Peak workstation CPUs (Wikipedia)
Facts last checked against these sources on . Page last edited on .