Socket FM1 socket: CPUs, chipsets and cooler fit
Socket FM1 is the AMD socketed platform for Llano desktop APUs and companion Athlon II CPUs. It carries 905 contacts in a PGA-ZIF socket on a 31 by 31 grid. AMD launched the socket in June 2011 with the A8-3850, followed by Athlon II X4 638 and 641 without graphics in February 2012.
Quick facts
| Maker | AMD |
|---|---|
| Package type | PGA |
| Contacts | 905 |
| Package size | n/a |
| Introduced | June 2011 |
| Status | Legacy |
| Memory | DDR3-1600 and 1866, two channels |
| PCIe from the CPU | PCIe 2.0 from the APU (16 graphics lanes plus 4 general purpose lanes) |
| Cooler mounting holes | 48 × 96 mm |
| Replaces | AM3 |
| Replaced by | Socket FM2 |
Overview
The socket carries K10 Stars CPU cores with Radeon HD 6000D series graphics on APU models. Power covers 65 W mainstream parts through 100 W unlocked K parts, with the board heatsink sized per class. Because the chip is socketed, a qualified replacement can be fitted without soldering, subject to BIOS support.
Socket FM1 was superseded by Socket FM2 for Trinity in October 2012 with 904 contacts and Piledriver cores. FM1 boards are therefore used or old stock. Memory type, display outputs and power limits follow the board design rather than the socket name.
Processor generations
| Codename | Marketing name | Years | Notes |
|---|---|---|---|
| Llano | A-series 3000 APUs and Athlon II X4 | 2011 to 2012 | K10 Stars based desktop APUs with VLIW5 graphics plus Athlon II X4 638 and 641 without graphics, launched in June 2011. |
Chipsets for Socket FM1
Hudson FCH (A55 and A75)
The controller hubs launched with Llano in June 2011 for Socket FM1 boards.
| Chipset | Segment | Notes |
|---|---|---|
| A75 | Mainstream | Native USB 3.0 with four ports and six SATA 6Gb/s ports. |
| A55 | Value | USB 2.0 with six SATA 3Gb/s ports for value boards. |
Socketed desktop package
Socket FM1 uses a 905-contact pin grid array with a zero insertion force lever. The processor carries the pins and drops into the socket, which suits repair and qualified upgrades. This differs from FM2, where a similar looking 904-contact socket carries Piledriver parts that never interchange.
In practice replacement depends on BIOS support. The board must list the exact model, since Llano APUs and Athlon derivatives share the socket but differ in graphics. A like for like swap is the safe case, and K to non-K moves need no wiring change.
Memory and I/O
Socket FM1 designs use DDR3 memory in two channels, commonly DDR3-1600 with DDR3-1866 on Athlon II X4 638 and 641 and larger APUs. Boards commonly offer four DIMM slots on ATX and two on micro ATX. Two matched modules give the rated bandwidth, which also feeds the graphics block on APU models.
PCI Express is PCIe 2.0 from the APU with 16 lanes for one graphics slot, plus chipset lanes for the rest. Most builds in this class stay on integrated graphics, while Athlon X4 builds need a separate card. The Socket vs chipset: what decides whether a CPU works guide covers AMD pairing rules.
Platform lifecycle
Socket FM1 covers Llano from June 2011 through 2012. AMD moved desktops to Socket FM2 for Trinity in October 2012, then to FM2+ for Kaveri. Compatible boards and spare chips are used or old stock.
For a working Socket FM1 desktop the practical path is maintenance: fresh thermal paste, clean fans, an SSD where the board allows, and a memory pair that matches. A platform move means a new socket with DDR3 or DDR4. The How to find your CPU socket type guide explains how to confirm the socket before ordering parts.
CPUs on Socket FM1
18 processor pages in the database, newest first.
| Processor | Cores / threads | Base / boost | TDP | Launched |
|---|---|---|---|---|
| AMD Athlon II X4 638 | 4 / 4 | 2.7 GHz | 65 W | Feb 2012 |
| AMD Athlon II X4 641 | 4 / 4 | 2.8 GHz | 100 W | Feb 2012 |
| AMD Athlon II X4 651K | 4 / 4 | 3.0 GHz | 100 W | Jan 2012 |
| AMD A4-3420 | 2 / 2 | 2.8 GHz | 65 W | Dec 2011 |
| AMD A6-3620 | 4 / 4 | 2.2 / 2.5 GHz | 65 W | Dec 2011 |
| AMD A6-3670K | 4 / 4 | 2.7 GHz | 100 W | Dec 2011 |
| AMD A8-3820 | 4 / 4 | 2.5 / 2.8 GHz | 65 W | Dec 2011 |
| AMD A8-3870K | 4 / 4 | 3.0 GHz | 100 W | Dec 2011 |
| AMD Athlon II X4 651 | 4 / 4 | 3.0 GHz | 100 W | Nov 2011 |
| AMD A4-3300 | 2 / 2 | 2.5 GHz | 65 W | Sep 2011 |
| AMD A4-3400 | 2 / 2 | 2.7 GHz | 65 W | Sep 2011 |
| AMD E2-3200 | 2 / 2 | 2.4 GHz | 65 W | Sep 2011 |
| AMD A6-3500 | 3 / 3 | 2.1 / 2.4 GHz | 65 W | Aug 2011 |
| AMD Athlon II X4 631 | 4 / 4 | 2.6 GHz | 100 W | Aug 2011 |
| AMD A6-3600 | 4 / 4 | 2.1 / 2.4 GHz | 65 W | Jun 2011 |
| AMD A6-3650 | 4 / 4 | 2.6 GHz | 100 W | Jun 2011 |
| AMD A8-3800 | 4 / 4 | 2.4 / 2.7 GHz | 65 W | Jun 2011 |
| AMD A8-3850 | 4 / 4 | 2.9 GHz | 100 W | Jun 2011 |
Frequently asked questions
Which processors fit Socket FM1?
Llano A-series APUs (A4, A6, A8, E2) plus Athlon II X4 parts 638 and 641 and Sempron X2 parts based on them. Trinity and Richland APUs need Socket FM2 despite the similar name.
Is Socket FM1 the same as Socket FM2?
No. FM1 is a 905-contact PGA for Llano K10 parts. FM2 is a 904-contact PGA for Piledriver parts. The pin count differs by one and parts do not move between them.
What memory does Socket FM1 use?
DDR3-1600 and 1866 over two 64 bit channels. Athlon II X4 638 and 641 reach DDR3-1866, while smaller APUs top out at lower speeds. Two matched DIMMs feed graphics best.
How many PCIe lanes does Socket FM1 provide?
PCIe 2.0 from the APU for one graphics slot with 16 lanes, plus 4 general purpose lanes and 4 lanes to the Fusion controller hub. A mainstream card of the era matches the 65 W APUs without waste.
Sources and verification
- Socket FM1 on Wikipedia (905 contacts, Llano)
- AMD A8-3850 Llano review (AnandTech, A55 and A75 chipsets)
- Noctua cooler compatibility (AM3 and FM1 shared mount)
Facts last checked against these sources on . Page last edited on .