AMD Ryzen Threadripper 3990X socket: sTRX4
The AMD Ryzen Threadripper 3990X uses sTRX4, the 4094-contact LGA socket for Threadripper HEDT processors. It is a 64-core Castle Peak chip at 280 W for TRX40 boards with 4-channel DDR4 memory.
- Socket
- sTRX4
- Launched
- February 7, 2020
- Cores and threads
- 64 and 128
- Default TDP
- 280 W
- Codename
- Castle Peak
- Segment
- HEDT
- Family
- AMD Ryzen Threadripper
- Clocks
- 2.9 / 4.3 GHz
AMD Ryzen Threadripper 3990X specifications
| Cores | 64 |
|---|---|
| Threads | 128 |
| Core architecture | Zen 2 (Castle Peak) |
| Clocks | 2.9 GHz base, up to 4.3 GHz boost |
| Cache | 256 MB L3, 32 MB L2 and 4096 KB L1 |
| Default TDP | 280 W |
| Manufacturing process | TSMC 7 nm FinFET with 12 nm IOD |
| Memory support | DDR4-3200, 4 channels, up to 256 GB |
| PCI Express | 64 PCIe Gen4 lanes from the CPU (56 usable), 16 from TRX40 |
| Integrated graphics | None (discrete card required) |
| Multiplier | Unlocked |
| ECC memory | Supported where the board enables it |
| Package | FC-LGA4094, socket sTRX4 |
| Cooler in the box | None, liquid cooling recommended |
| Launch price | $3990 manufacturer recommended price at launch |
Motherboard and chipset compatibility
AMD Ryzen Threadripper 3990X needs a motherboard with a sTRX4 socket. The table shows which chipset series accept it.
| Series | Chipsets | Support |
|---|---|---|
| TRX40 HEDT | TRX40 | 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 sTRX4.
sTRX4 at a glance
| Type | LGA, 4,094 contacts |
|---|---|
| Package size | 58.5 × 75.4 mm |
| Introduced | November 2019 |
| Memory | DDR4-3200 ECC UDIMM, 4 channels, up to 256 GB |
| Cooler mounting holes | Large TR4-SP3 mount (sTRX4, sWRX8, TR4 and SP3 compatible) |
What the Threadripper 3990X is
The Ryzen Threadripper 3990X is the sixty four core flagship of the Castle Peak HEDT range that AMD launched on February 7 2020 for sTRX4 boards. Its Zen 2 cores run 2.9 GHz base with boost up to 4.3 GHz across 128 threads. Cache is 256 MB of L3 with 32 MB of L2 and 4096 KB of L1, built from eight chiplets plus a large I/O die on TSMC 7 nm FinFET with 12 nm I/O.
Sixty four cores suit single socket throughput for rendering, video work and compilation at HEDT memory limits. The 2.9 GHz base exceeds the 2.7 GHz base of the PRO 3995WX workstation twin, which helps desktop responsiveness while keeping the same thread count. Four DDR4 channels feed the cores with ECC where the board enables it, and 64 Gen4 lanes cover GPUs and NVMe.
AMD rates the chip at 280 W default TDP with unlocked multiplier for HEDT tuning. The sTRX4 package carries 4094 contacts in a large LGA with carrier frame, and discrete graphics are required. The 95 C maximum operating temperature guides HEDT airflow with liquid cooling recommended for sustained all-core runs.
Socket and motherboard compatibility
The 3990X fits sTRX4 on TRX40 with 4 DDR4 channels. Workstation sWRX8 operation with 8 channels needs a PRO chip such as the AMD Ryzen Threadripper PRO 3995WX, so HEDT planning centres on TRX40 board choice. BIOS support for Castle Peak must be installed from the maker page. The LGA socket uses three Torx screws in order with the carrier frame.
TRX40 boards for 64 cores are HEDT flagships with multi GPU layouts and fast storage arrays. Power stages target 280 W sustained across eight chiplets, so dual EPS and clean case airflow are requirements. Memory population with UDIMM modules follows four channels to 256 GB, with 4 by 1R kits at 3200 MT/s and denser kits at lower speeds per the AMD memory table.
The HEDT flagship suits creators who need threads without PRO management features. Buyers who need 8-channel ECC and 128 lanes choose PRO on sWRX8 instead, while those who stay under 256 GB and use fewer lanes save notably with TRX40. The LGA, PGA and BGA: CPU package types explained guide places sTRX4 LGA handling against desktop sockets for builders new to Threadripper torque procedures.
Memory, PCIe and cooling
DDR4 to DDR4-3200 in 4 channels with ECC where the board routes it gives capacity to 256 GB with UDIMM modules. Primary slots first per manual, with 4 by 1R kits at 3200 MT/s, 8 by 1R kits at 2933 MT/s and 8 by 2R kits at 2677 MT/s on the 3990X. Larger layouts need board validation for timing, since HEDT stability favours validated speeds.
PCIe from the CPU gives 64 Gen4 lanes with 56 usable plus 16 Gen4 lanes from TRX40 for NVMe RAID and high speed networking. HEDT boards split lanes between multiple GPUs, NVMe arrays and 10 Gb networking, with the exact split fixed per board. Cooling needs a 280 W HEDT liquid unit in most flagship builds, because 64 cores hold high power under all-core rendering. No box cooler is included.
ECC on TRX40 depends on board wiring. Boards that route ECC with UDIMM correct single bit errors in long renders, while others run non-ECC for higher speeds. Population with matched kits beats mixed modules for bandwidth where 64 cores share four channels.
Upgrade paths
On TRX40 the practical steps down are 24-core and 32-core Castle Peak HEDT parts for higher clocks at lower thread counts, while many owners gain more from GPU or storage steps first. Filling 4 channels and adding fast NVMe help huge projects without leaving the socket. The 64-core chip already holds the thread ceiling on sTRX4, so core steps trade threads for clocks.
Moving to PRO on sWRX8 with the AMD Ryzen Threadripper PRO 3995WX adds channels to eight and lanes to 128 with a board change for memory heavy work. For most 3990X owners the value order is memory to full 256 GB, then GPUs, then storage fabric on the same sTRX4 socket.
Used buyers check BIOS and cooling first. A TRX40 board that shipped with a 24-core part in 2019 needs a BIOS with Castle Peak flagship support before running a 3990X, plus a 280 W loop with even mounting pressure. The unlocked multiplier allows HEDT tuning with Ryzen Master where cooling allows, but the main gain is out of box threads rather than manual clocks.
Frequently asked questions
What socket does the Threadripper 3990X use?
Socket sTRX4 (LGA 4094) on TRX40 with 4 DDR4 channels. It needs Castle Peak HEDT BIOS support and does not work in sWRX8 or TR4 boards.
What memory does the 3990X use?
DDR4-3200 in 4 channels to 256 GB with UDIMM modules and ECC where the board enables it. Denser 8-stick kits run at 2933 MT/s or 2677 MT/s per the AMD memory table.
How many cores does the 3990X have?
Sixty four cores and 128 threads at 2.9 GHz base and up to 4.3 GHz boost, with 256 MB L3 and a 280 W TDP for flagship HEDT throughput.
Is the 3990X good for gaming?
It runs creation work with discrete GPUs and the multiplier is unlocked for HEDT tuning, but gaming alone does not use 64 cores well. High thread counts help renders and compiles, while 280 W cooling and TRX40 board cost exceed gaming needs.
Sources and verification
- AMD Ryzen Threadripper 3990X specifications (AMD)
- Socket sTRX4 - 4094 contacts and TRX40 (Wikipedia)
- Zen 2 Castle Peak HEDT CPUs (Wikipedia)
Facts last checked against these sources on . Page last edited on .