AMD Ryzen 9 PRO 9955 socket: AM5
The AMD Ryzen 9 PRO 9955 uses the AM5 socket. It is a 12-core Zen 5 desktop processor at 120 W for balanced workstation builds, running on 800 series boards out of the box and on 600 series boards after a BIOS update.
- Socket
- AM5
- Launched
- June 30, 2026
- Cores and threads
- 12 and 24
- Default TDP
- 120 W
- Codename
- Granite Ridge
- Segment
- Desktop
- Family
- AMD Ryzen 9
- Clocks
- 3.4 / 5.4 GHz
AMD Ryzen 9 PRO 9955 specifications
| Cores | 12 |
|---|---|
| Threads | 24 |
| Core architecture | Zen 5, two CCDs with 12 active cores |
| Clocks | 3.4 GHz base, up to 5.4 GHz boost |
| Cache | 64 MB L3 and 12 MB L2 |
| Default TDP | 120 W |
| Manufacturing process | TSMC 4 nm FinFET, 6 nm I/O die |
| Memory support | DDR5 up to 5600 MT/s, two channels, up to 256 GB |
| PCI Express | PCIe 5.0, 28 lanes (24 usable) |
| Integrated graphics | AMD Radeon Graphics, 2 compute units (up to 2200 MHz) |
| Multiplier | Locked |
| ECC memory | Yes (requires board support) |
| Package | AM5 (LGA1718) |
| Maximum temperature | 95 C |
| Cooler in the box | None |
Motherboard and chipset compatibility
AMD Ryzen 9 PRO 9955 needs a motherboard with a AM5 socket. The table shows which chipset series accept it.
| Series | Chipsets | Support |
|---|---|---|
| 800 series | X870E, X870, B850, B840 | Works out of the box |
| 600 series | X670E, X670, B650E, B650, A620 | Needs a BIOS update Needs a BIOS update on boards built before the Ryzen 9000 launch. Check the board maker's CPU support list. |
Board makers publish a CPU support list for every model. Check it for your exact board before buying. Chipset details for AM5.
Recommended GPU pairing
| Recommended tier | High-end 1440p |
|---|---|
| Example GPUs | GeForce RTX 5070, Radeon RX 9070 |
| Target resolution | 1440p high settings |
Twelve Zen 5 cores with PCIe 5.0 lanes and DDR5-5600 fit high-end 1440p cards from 2026. A faster card still works and the balance shifts with game, settings and resolution.
This is a rough match for a new build at the stated resolution, not a limit. A faster card still works and helps at higher resolutions or in games that load the GPU more than the CPU. A slower card is fine for lighter games and office use. The exact balance shifts with the game, the settings and the resolution, so no percentage is given.
AM5 at a glance
| Type | LGA, 1,718 contacts |
|---|---|
| Package size | 40 × 40 mm |
| Introduced | September 2022 |
| Memory | DDR5 only (AMD EXPO profiles for faster kits) |
| Cooler mounting holes | 54 × 90 mm |
What the Ryzen 9 PRO 9955 is
The AMD Ryzen 9 PRO 9955 is a 12-core, 24-thread desktop processor that AMD listed for June 30, 2026 in the Ryzen PRO 9000 series. It uses the Granite Ridge design with Zen 5 cores on AM5, with a base clock of 3.4 GHz and boost up to 5.4 GHz. The cache totals 64 MB of L3 beside 12 MB of L2 across two complexes, and AMD rates the default TDP at 120 W. The compute cores use TSMC 4 nm FinFET with a 6 nm I/O die.
Twelve cores sit in the middle of the PRO range for buyers who need more than 8 cores without the 170 W envelope of the 16-core parts. It matches the 65 W Ryzen 9 PRO 9945 on clocks and cache, while the higher 120 W limit allows stronger sustained speeds in rendering, compilation and analysis. For short bursts the two behave closely, while longer jobs separate them.
Basic display comes from AMD Radeon Graphics with 2 compute units up to 2200 MHz. The multiplier is locked, and AMD lists no support for EXPO, Precision Boost Overdrive or Curve Optimizer on this PRO model. ECC memory is supported when the board provides it, and the maximum operating temperature is 95 C.
Socket and motherboard compatibility
The 9955 fits the AM5 socket with 1,718 contacts. Boards with 800 series chipsets such as X870E, X870, B850 and B840 accept it out of the box. Boards with 600 series chipsets such as X670E, X670, B650E, B650 and A620 accept it after a BIOS update that adds Ryzen PRO 9000 support. The board maker CPU support list names the minimum version.
A 600 series board built before that support will not start with this chip until firmware is updated. Boards with BIOS Flashback can write firmware without a processor in place, while other boards need a supported older chip for the update step. Offices that reuse boards should confirm firmware before a fleet swap.
The related AMD Ryzen 5 9600X shares the same socket and DDR5 path and marks the 6-core consumer end for comparison. The 9955 suits mainstream workstation boards with decent power delivery, without demanding flagship VRM designs. Current BIOS and chipset drivers keep boost and power management on track.
Memory, PCIe and cooling
The memory controller supports DDR5 up to 5600 MT/s with two modules, and slower speeds with four modules, across two channels to 256 GB. AMD lists DDR5-5600 for 2x1R and 2x2R configurations and DDR5-3600 for 4x1R and 4x2R configurations. There is no DDR4 option on AM5. ECC UDIMM is supported when the board wires it, which suits creator and office machines that keep large projects in memory.
The processor provides 28 PCIe 5.0 lanes with 24 usable for devices, typically a graphics slot and NVMe storage at Gen5 speed on boards wired for it. A high-end 1440p card matches the 12-core throughput at 1440p high settings, with fast NVMe alongside for project files. Chipset lanes cover the remaining board devices.
A 120 W default TDP needs a competent tower air cooler or equivalent, since AMD includes no cooler with this tray model. The mounting pattern is the shared 54 by 90 mm of AM4 and AM5, so many existing coolers carry over with AM5 hardware. The CPU cooler compatibility by socket guide covers the patterns and the fixed AM5 backplate rule. Steady case airflow helps all-core jobs hold clocks.
Upgrade paths
On the same socket the 65 W Ryzen 9 PRO 9945 offers the same 12 cores with the same cache for compact and quiet builds. The 16-core Ryzen 9 PRO 9965 adds four cores at 170 W for heavier parallel work, while the 16-core Ryzen 9 PRO 9965X3D adds stacked cache as well. All share boards and DDR5 with a BIOS check.
The 8-core Ryzen 7 PRO 9755 sits below for general office fleets, and the 6-core Ryzen 5 PRO 9655 sits lower still for cost sensitive seats. A move among these keeps cooler hardware in place when ratings allow.
Coming from AM4, the move means a new board and DDR5 memory, since neither transfers. Some coolers transfer with AM5 hardware. AMD has stated AM5 support through 2029, so the platform keeps later CPU options open.
Frequently asked questions
What socket does the AMD Ryzen 9 PRO 9955 use?
It uses AM5, an LGA socket with 1,718 contacts. It needs an AM5 board with DDR5 memory.
Does the 9955 work on a B650 motherboard?
Yes, after a BIOS update that adds Ryzen PRO 9000 support. 800 series boards accept it out of the box.
What is the difference between the PRO 9955 and the PRO 9945?
Both have 12 cores and 24 threads at 3.4 GHz to 5.4 GHz with 64 MB of L3. The 9945 holds a 65 W envelope with a Wraith Stealth cooler, while the 9955 allows 120 W with no cooler included for stronger sustained performance.
Does the 9955 support ECC memory?
Yes, when the board provides ECC support. AMD lists ECC as Yes with board support required.
Is the 9955 unlocked for overclocking?
No. AMD lists overclocking as not supported on this PRO model. It runs with Precision Boost 2 within its ratings.
Sources and verification
- AMD Ryzen 9 PRO 9955 (AMD)
- AMD Expands Ryzen PRO 9000 Series Processor Lineup (TechPowerUp)
- AMD expands its Ryzen 9000 PRO lineup with six new SKUs (Tom's Hardware)
Facts last checked against these sources on . Page last edited on .