AMD A8-3870K socket: Socket FM1
The AMD A8-3870K uses the Socket FM1 socket. It is a 100 W unlocked quad core Llano APU at 3.0 GHz with Radeon HD 6550D graphics.
- Socket
- Socket FM1
- Launched
- December 2011
- Cores and threads
- 4 and 4
- Default TDP
- 100 W
- Codename
- Llano
- Segment
- Desktop
- Family
- AMD A8
- Clocks
- 3.0 GHz
AMD A8-3870K specifications
| Cores | 4 |
|---|---|
| Threads | 4 |
| Core architecture | Stars (K10) cores on 32 nm |
| Clocks | 3.0 GHz (no turbo) |
| Cache | 4 MB L2 (1 MB per core) |
| Default TDP | 100 W |
| Manufacturing process | 32 nm |
| Memory support | DDR3 up to 1866 MT/s, two channels |
| PCI Express | PCIe 2.0 from the APU |
| Integrated graphics | AMD Radeon HD 6550D (600 MHz, unlocked) |
| Multiplier | Unlocked |
| Package | Socket FM1 (PGA, 905 contacts) |
Motherboard and chipset compatibility
AMD A8-3870K needs a motherboard with a Socket FM1 socket. The table shows which chipset series accept it.
| Series | Chipsets | Support |
|---|---|---|
| Hudson FCH (A55 and A75) | A75, A55 | 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 Socket FM1.
Socket FM1 at a glance
| Type | PGA, 905 contacts |
|---|---|
| Package size | n/a |
| Introduced | June 2011 |
| Memory | DDR3-1600 and 1866, two channels |
| Cooler mounting holes | 48 × 96 mm |
What the A8-3870K is
AMD A8-3870K is an unlocked quad core Llano APU that AMD released in December 2011 for tuning desktops. It uses the Stars K10 core design on a 32 nm process, running at 3.0 GHz with no turbo. The cache is 4 MB of L2 with 1 MB per core. Power is 100 W. Graphics come from AMD Radeon HD 6550D with 400 shaders at 600 MHz. The K suffix unlocks both the CPU multiplier and the graphics clock, without adding Turbo Core.
Unlocked operation needs an A75 board with multiplier control and cooling above stock. At stock the chip behaves like a fast 100 W quad, with all core work at 3.0 GHz. Reviewers reached 800 MHz on the graphics with tuning. Threads equal cores at 4.
Towers pair it with 4 GB to 8 GB of DDR3 and a SATA drive. The 100 MHz step over the A8-3850 plus unlocked clocks mark the top of the Llano line. The LGA, PGA and BGA: CPU package types explained guide places this PGA desktop part against BGA mobile forms.
Socket and motherboard compatibility
The A8-3870K drops into Socket FM1 on A55 and A75 boards. Multiplier control needs an A75 board with tuning firmware; A55 boards run the chip at stock clocks. Late 2011 models need a BIOS new enough to list the exact A8-3870K string.
Power at 100 W needs a standard tower board with a full size cooler. The Socket vs chipset: what decides whether a CPU works guide covers AMD pairing rules.
Memory, PCIe and cooling
Memory support is DDR3 up to 1866 MT/s, two channels. Two matched modules feed four cores and shared graphics. Faster DIMMs through overclocking profiles help both.
PCI Express is PCIe 2.0 from the APU for one graphics slot. Most builds stay on the unlocked HD 6550D, which tunes with the CPU.
Cooling at stock follows the 100 W pattern, but overclocking wants a tower cooler with headroom. The shared AMD mount keeps choice wide.
Upgrade paths
On Socket FM1 the A8-3870K already tops the Llano range, so faster moves mean a platform change. Memory and storage carry over to FM2 DDR3 builds. A locked comparison at lower clocks is AMD A8-3850 on the same socket.
A platform move to Socket FM2 needs a new board while DDR3 often carries over.
Frequently asked questions
What socket does the AMD A8-3870K use?
It uses Socket FM1. Multiplier control needs an A75 board with tuning firmware.
Is the A8-3870K unlocked?
Yes. Both the CPU multiplier and the graphics clock are unlocked. There is no Turbo Core.
What memory does the A8-3870K use?
DDR3 up to 1866 MT/s, two channels, with faster speeds through overclocking.
Does the A8-3870K need a separate graphics card?
No. Radeon HD 6550D covers office displays, video and light games, and it overclocks with the CPU.
Sources and verification
Facts last checked against these sources on . Page last edited on .