AMD A6-6400K socket: Socket FM2

What the A6-6400K is

AMD A6-6400K is a dual core Richland APU for Socket FM2 that AMD released in June 2013. It runs 2 Piledriver cores and 2 threads at 3.9 GHz base with turbo to 4.1 GHz. The cache is 1 MB L2 (no L3). Power is 65 W on a 32 nm process. Graphics come from AMD Radeon HD 8470D (800 MHz), which drives desktop monitors without a separate card.

The cores sit in Piledriver modules with 1 mb l2 in total, and threads equal cores at 2. The on die graphics block is AMD Radeon HD 8470D (800 MHz), which shares system memory. That sharing is why two matched DDR3 modules matter more here than on a CPU without graphics. Memory support is ddr3 up to 1866 mt/s, two channels. The APU also carries pcie 2.0 from the apu, while SATA and USB come from the board chipset.

At 65 W the A6-6400K fits slim towers with stock cooling. The 3.9 GHz base keeps everyday work responsive, while turbo to 4.1 GHz helps foreground bursts. DDR3 speed follows the memory controller rating, and the board manual lists qualified kits. The Socket vs chipset: what decides whether a CPU works guide explains AMD pairing on FM2.

Socket and motherboard compatibility

The A6-6400K fits Socket FM2 on A55 through A85X boards. Most Socket FM2+ boards accept it after a BIOS check, since FM2+ keeps back compatibility with Richland. The reverse never works for Kaveri Steamroller parts, which need FM2+. DDR3 modules match stock operation without tuning. The 9 series chipset names belong to AM3+, not to FM2, so FM1 Llano boards never accept Richland.

Power delivery on FM2 is modest compared with AM3+. The 65 W rating suits all FM2 power designs. A board that lists Richland support is the safe choice. The CPU cooler compatibility by socket guide explains the 48 by 96 mm pattern shared with AM2, AM3 and FM1. FM2 coolers usually carry over within that group, while AM4 needs a new bracket.

Memory, PCIe and cooling

Memory support is ddr3 up to 1866 mt/s, two channels across two channels. 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. There is no DDR4 option, so a move to DDR4 means leaving the socket.

PCI Express is pcie 2.0 from the apu from the APU for one graphics slot, with SATA and USB from the board chipset. Most builds in this class stay on integrated graphics, since AMD Radeon HD 8470D covers office work and video. A mainstream card of the era pairs without waste where a slot is free. NVMe boot support depends on the board, not on the APU alone.

Cooling follows the 65 W rating. The stock cooler suits office loads, while a compact tower helps sustained tasks. The 48 by 96 mm mounting pattern is shared with AM2, AM3 and FM1, so an older AMD cooler often fits. Check height clearance in slim cases before reusing a tall tower.

Upgrade paths

Within Socket FM2 the A6-6400K sits in the dual core group for office builds. A same socket move can add cores or clocks, for example from an A4 to an A8, or from a locked part to an unlocked K part for tuning. The board stays, while memory and cooler often carry over. AMD A4-7300 shows another Richland option on the same socket.

A platform move means a new socket with DDR4. AMD moved mainstream desktops to AM4 with a different pin layout and cooler spacing, and a processor like AMD A4-7300 shows the newer design. That move needs a new board, new DDR4 modules and often a new cooler bracket. Keep the FM2 board for secondary duty where it still runs well.