AMD A4-3420 socket: Socket FM1

What the A4-3420 is

AMD A4-3420 is a dual core Llano APU that AMD released in December 2011 for socketed desktops. It uses the Stars K10 core design on a 32 nm process, running at 2.8 GHz with no turbo. The cache is 1 MB of L2 with 512 KB per core. Power is 65 W. Graphics come from AMD Radeon HD 6410D with 160 shaders at 600 MHz.

The late 2011 timing places it as the fastest stock A4 dual of the Llano generation, 100 MHz above the A4-3400 at the same power and graphics. Two cores at 2.8 GHz cover office multitasking with direct single thread response. The 1,178 million transistor die integrates cores, graphics and the memory controller.

Office towers pair it with A55 or A75 boards and an SSD for a quick feel. Fixed clocks suit fleet images that must behave identically. The How to find your CPU socket type guide shows how to confirm the socket.

Socket and motherboard compatibility

The A4-3420 drops into Socket FM1 on A55 and A75 boards. Late 2011 models need a BIOS new enough to list the exact A4-3420 string. DDR3 modules match stock operation without tuning.

Power at 65 W suits standard desktop boards. The CPU cooler compatibility by socket guide explains the shared AMD mount.

Memory, PCIe and cooling

Memory support is DDR3 up to 1866 MT/s, two channels. Two matched modules feed cores and shared graphics. Contemporary reports sometimes cite DDR3-1600 for this SKU against the database DDR3-1866 figure; either speed runs within spec on A75 boards.

PCI Express is PCIe 2.0 from the APU for one graphics slot. Most builds stay on integrated graphics.

Cooling follows the 65 W rating with a stock heatsink and case airflow.

Upgrade paths

On Socket FM1 the A4-3420 already tops the stock A4 dual range, so same socket moves mean A6 or A8 APUs with more cores or Athlon quads. Memory and storage carry over. A slower dual reference is AMD A4-3400 on the same socket.

A platform move to Socket FM2 needs a new board while DDR3 often carries over.