Socket FM1
Socket FM1 is a 905-pin organic pin grid array (OPGA) CPU socket designed by AMD for mid-range and budget desktop computers, introduced in mid-2011 to support the Llano microarchitecture-based A-series accelerated processing units (APUs) and derived Athlon II processors built on a 32 nm process.[1][2] The socket features a 31x31 pin grid with specific plugged holes for alignment and compatibility, enabling dual-channel DDR3 memory support up to 1866 MHz across up to four DIMMs or SODIMMs, with a maximum bandwidth of approximately 29.9 GB/s.[1][3] It accommodates processors with two to four cores clocked up to 3.0 GHz or higher in unlocked models, including integrated Radeon HD 6000-series graphics in APU variants for enhanced multimedia and light gaming performance without discrete GPUs.[2][1] Compatible chipsets include the AMD A55 and A75, providing features such as PCIe 2.0 lanes and integrated audio, with the A75 additionally supporting USB 3.0 ports, targeting cost-effective systems for everyday computing.[3] Supported processors encompass the A4 (dual-core), A6 (triple-core), A8 (quad-core), and E2 (dual-core) series, alongside Athlon II X2 and X4 models and Sempron X2, with thermal design powers ranging from 65 W to 100 W.[1][4] The platform emphasized integrated graphics acceleration, supporting DirectX 11 and up to six simultaneous displays in some configurations, marking an early step in AMD's fusion of CPU and GPU technologies.[2] Socket FM1 was short-lived, superseded by FM2 in 2012 for Trinity and later APUs, but remains notable for pioneering affordable all-in-one processing solutions.[1]Design and Specifications
Physical Characteristics
The Socket FM1 employs a Pin Grid Array-Zero Insertion Force (PGA-ZIF) design featuring 905 pins within an Organic Pin Grid Array-905 (OPGA-905) package.[3] This socket measures 40 mm × 40 mm, with a pin pitch of 1.27 mm, and is engineered for desktop motherboard integration via a lever-actuated retention mechanism that facilitates straightforward CPU installation and removal.[3] Its pin configuration forms a 31 × 31 grid, with 13 corner pins plugged and additional omissions for keying, enabling efficient signal and power distribution optimized for the thermal demands of Llano-era APUs rated up to 100 W TDP.[3][2] Cooler compatibility requires mounting hole spacing of 96 mm × 48 mm, aligning with AMD's retention standards shared across FM1 and earlier AM-series sockets.[5]Electrical and Interface Specifications
Socket FM1 processors utilize a core voltage range of 0.8 V to 1.45 V, managed through the Serial VID Interface (SVI) for dynamic adjustment based on load conditions, with dynamic voltage scaling via the Serial VID Interface (SVI), which allows for efficient power management with reduced external components.[6] The socket's primary interface for CPU-to-chipset communication is the Unified Media Interface (UMI), operating as an x4 link at up to 5 GT/s with a 100 MHz system clock, enabling high-bandwidth data transfer for APU-integrated features while maintaining compatibility with the Fusion Controller Hub (FCH).[6] Power delivery for Socket FM1 requires a voltage regulator module (VRM) compliant with AMD's specifications, typically featuring 4 phases or more to handle thermal design power (TDP) ratings of 65 W to 100 W across supported APUs, with a maximum current draw per pin limited to 1 A to ensure socket integrity and prevent overheating.[6][7][8] Thermal design parameters allow for a maximum junction temperature of 95 °C, incorporating socket-level integration with the processor's heat spreader to facilitate direct cooling solutions and maintain operational stability under load.[6]Supported Components
Compatible Chipsets
The Socket FM1 platform utilizes AMD's Fusion Controller Hubs (FCH), specifically the A75 and A55 models, as its compatible chipsets, introduced in 2011 alongside the Lynx platform to integrate southbridge functions for I/O management.[9] These chipsets handle essential peripherals while the APU manages memory and primary graphics PCIe lanes, enabling efficient system designs for entry-level desktops. The primary chipset, AMD A75 (codenamed Hudson-D3), delivers robust connectivity with up to 8 PCIe 2.0 lanes configurable for expansion cards or secondary graphics, dual-channel DDR3 memory support up to 1866 MHz via the APU, and 6 SATA 6 Gb/s ports for high-speed storage.[10] It includes native support for 4 USB 3.0 ports and up to 10 USB 2.0 ports, HD audio codecs, and enables full APU overclocking alongside AMD CrossFire for multi-GPU setups combining integrated and discrete graphics. Budget-oriented options center on the AMD A55 (codenamed Hudson-D2), which features reduced PCIe 2.0 lane configurations (typically 4-6 lanes, limited to x4 for secondary slots), the same dual-channel DDR3 up to 1866 MHz, and 6 SATA 3 Gb/s ports for basic storage needs.[10] This chipset supports up to 14 USB 2.0 ports, integrated HD audio, and single Gigabit Ethernet on compatible motherboards, but lacks native USB 3.0 and restricts advanced overclocking or multi-GPU to single-graphics AMD Dual Graphics modes. Key differences lie in performance and expandability: the A75 facilitates premium features like faster SATA, USB 3.0, and CrossFire for enhanced gaming or productivity, whereas the A55 prioritizes cost-effective I/O for everyday computing without overclocking or high-bandwidth peripherals.[9] Both chipsets integrate southbridge capabilities for up to 14 USB 2.0 ports in the A55 variant and standard audio processing, ensuring broad compatibility within the 2011 Lynx ecosystem.[10]Compatible Processors
Socket FM1 supports a range of AMD processors based on the Llano architecture, utilizing the 32 nm K10.5 (Family 12h) process with integrated memory controllers for dual-channel DDR3 support. These include the A-series and E2-series Accelerated Processing Units (APUs), which feature fused CPU and GPU dies, Athlon II variants derived from the same silicon but with the graphics cores disabled to offer cost-effective CPU-only options, and Sempron X2 models. All models are designed for mid-range and budget desktop systems, emphasizing integrated graphics performance in APU variants for light gaming and multimedia tasks without discrete GPUs.[3] The A-series and E2-series APUs represent the primary compatible processors, with ten models released between 2011 and 2012. These quad-, triple-, and dual-core chips integrate Radeon HD 6000-series graphics directly on the die, providing up to 400 shaders and DirectX 11 support for enhanced visual computing. Representative examples include the flagship A8-3850, a quad-core APU clocked at 2.9 GHz base with Radeon HD 6550D integrated graphics (up to 600 MHz GPU clock) and a 100 W TDP, suitable for mainstream productivity and casual gaming. The unlocked A8-3870K offers four cores at a 3.0 GHz base (turbo to 3.1 GHz), Radeon HD 6550D graphics, and 100 W TDP. The A6-3670K variant offers four cores at a 2.7 GHz base (turbo to 2.8 GHz), Radeon HD 6530D graphics, and 100 W TDP, while the triple-core A6-3500 provides three cores at 2.1 GHz (turbo to 2.4 GHz), Radeon HD 6530D graphics, and a 65 W TDP. The entry-level A4-3400 provides two cores at 2.7 GHz, Radeon HD 6410D graphics, and a 65 W TDP for energy-efficient builds, and the E2-3200 offers two cores at 2.4 GHz with Radeon HD 6370D graphics and 65 W TDP. The complete lineup encompasses additional models such as the A8-3800 (quad-core, 2.4 GHz, 65 W), A6-3650 (quad-core, 2.6 GHz, 100 W), and A4-3300 (dual-core, 2.5 GHz, 65 W), all sharing 1 MB L2 cache per core and supporting up to 32 GB of DDR3-1866 memory.[11][12] Athlon II processors for Socket FM1 are non-APU variants binned from Llano dies, focusing on pure CPU performance without integrated graphics, thus requiring discrete GPUs for display output. Key quad-core examples are the Athlon II X4 651 (3.0 GHz, 95 W TDP), X4 641 (2.8 GHz, 95 W TDP), X4 638 (2.7 GHz, 65 W TDP), and X4 631 (2.6 GHz, 100 W TDP), each with 1 MB L2 cache per core for budget multi-threaded workloads. Dual-core options include the Athlon II X2 255 (3.1 GHz, 25 W TDP) and X2 221 (2.8 GHz, 25 W TDP), optimized for low-power systems with 1 MB L2 cache total. The Sempron X2 198 (2.5 GHz, 65 W TDP) provides an even more budget-oriented dual-core option without iGPU. These models, like the APUs, leverage the same 32 nm process but prioritize affordability over integrated compute.[12]| Model | Cores | Base Clock (GHz) | iGPU | TDP (W) | Notes |
|---|---|---|---|---|---|
| A8-3850 | 4 | 2.9 | Radeon HD 6550D | 100 | Mainstream APU |
| A8-3870K | 4 | 3.0 | Radeon HD 6550D | 100 | Unlocked multiplier |
| A6-3670K | 4 | 2.7 | Radeon HD 6530D | 100 | Unlocked multiplier |
| A6-3500 | 3 | 2.1 | Radeon HD 6530D | 65 | Triple-core APU |
| A4-3400 | 2 | 2.7 | Radeon HD 6410D | 65 | Entry-level APU |
| A4-3300 | 2 | 2.5 | Radeon HD 6410D | 65 | Entry-level APU |
| E2-3200 | 2 | 2.4 | Radeon HD 6370D | 65 | Budget APU |
| Athlon II X4 651 | 4 | 3.0 | None | 95 | CPU-only quad-core |
| Athlon II X4 641 | 4 | 2.8 | None | 95 | CPU-only quad-core |
| Athlon II X2 221 | 2 | 2.8 | None | 25 | Low-power dual-core |
| Sempron X2 198 | 2 | 2.5 | None | 65 | Budget dual-core |