AMD Athlon II X4 651K socket: Socket FM1
The AMD Athlon II X4 651K uses the Socket FM1 socket. It is a 100 W unlocked quad core Llano part at 3.0 GHz without graphics for tuning desktops.
- Socket
- Socket FM1
- Launched
- January 2012
- Cores and threads
- 4 and 4
- Default TDP
- 100 W
- Codename
- Llano
- Segment
- Desktop
- Family
- AMD Athlon II X4
- Clocks
- 3.0 GHz
AMD Athlon II X4 651K 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, no L3) |
| 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 CPU |
| Integrated graphics | None |
| Multiplier | Unlocked |
| Package | Socket FM1 (PGA, 905 contacts) |
Motherboard and chipset compatibility
AMD Athlon II X4 651K 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 Athlon II X4 651K is
AMD Athlon II X4 651K is an unlocked quad core Llano processor that AMD released in the first quarter of 2012 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 and no L3. Power is 100 W. There are no integrated graphics, so a separate card is required. The K suffix marks an unlocked multiplier, confirmed by the part number and the unlocked flag against locked for the 631 and 651. The list entry dating it to November 2011 conflicts with the APU list placing it in the first quarter of 2012, which is used here.
Unlocked operation needs an A75 board with multiplier control and cooling above stock. At stock the chip matches the X4 651 clock for clock, with headroom above 3.0 GHz for tuned builds. Threads equal cores at 4.
Towers pair it with 4 GB to 8 GB of DDR3 and a discrete card. The unlocked multiplier suits benches that tune K10 quads on FM1 boards. The How to find your CPU socket type guide shows how to confirm the socket.
Socket and motherboard compatibility
The Athlon II X4 651K fits Socket FM1 on A55 and A75 boards. Multiplier control needs an A75 board with tuning firmware; A55 boards run the chip at stock clocks. The board BIOS must list the exact X4 651K 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. Faster DIMMs through overclocking profiles help tuned builds.
PCI Express is PCIe 2.0 from the CPU for one graphics slot with 16 lanes. A mainstream card of the era pairs without waste.
Cooling at stock follows the 100 W pattern, but overclocking wants a tower cooler with headroom.
Upgrade paths
On Socket FM1 the Athlon II X4 651K already tops the Athlon range, so faster moves mean Llano APUs with graphics or a platform change. Memory, storage and the graphics card carry over. A locked comparison at the same clocks is AMD Athlon II X4 651 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 Athlon II X4 651K use?
It uses Socket FM1. Multiplier control needs an A75 board with tuning firmware.
Is the Athlon II X4 651K unlocked?
Yes. The K suffix marks an unlocked multiplier, unlike the locked 631 and 651.
What memory does the Athlon II X4 651K use?
DDR3 up to 1866 MT/s, two channels, with faster speeds through overclocking.
Does the Athlon II X4 651K have integrated graphics?
No. It needs a separate graphics card for any display output.
Sources and verification
Facts last checked against these sources on . Page last edited on .