AMD Phenom II X4 850 socket: Socket AM3

What the Phenom II X4 850 is

AMD Phenom II X4 850 is a quad core Propus processor that AMD released in June 2011 for mainstream desktops. It uses the K10 core design on a 45 nm process, running at 3.3 GHz with no turbo. The cache is 2 MB of L2 with 512 KB per core and no L3, which marks it as an Athlon II X4 die under the Phenom name. Power is 95 W. The retail box carries part number HDX850WFK42GM on a Propus C3 stepping. The HyperTransport link runs at 2.0 GHz to the 7 and 8 series chipset, and the 938-pin package fits the 941-hole AM3 socket as well as 942-contact AM3+ sockets.

The 100 MHz step over the 840 is the only change in kind, but it led Propus quads on fixed clocks at the time. Four cores at 3.3 GHz cover office multitasking and light threaded work. The chip keeps the dual channel DDR2 and DDR3 controller.

Towers pair it with 880G or 890GX boards and chipset video or a basic card. The fixed 3.3 GHz rate leads Propus quads on clocks, which shows in single thread office tasks. The 95 W rating wants a tower with fair airflow, since slim office chassis throttle sustained loads. The fixed 3.3 GHz rate leads Propus quads on clocks, which shows in single thread office tasks. Fixed clocks keep behavior predictable for fleets. The How to find your CPU socket type guide shows how to confirm the socket.

Socket and motherboard compatibility

The Phenom II X4 850 drops into Socket AM3 on 7 and 8 series boards with Propus support. AM3 processors also fit AM3+ boards. Check the maker CPU list for the exact board BIOS.

Power at 95 W needs a standard tower board with a full size cooler. Common homes include 770, 785G, 880G and 890GX boards, with 785G and 880G adding chipset video. Four 4 GB UDIMMs give the practical 16 GB ceiling, with ECC only where the board wires it. Boards with four DIMM slots reach the ceiling with matched kits, while two slot boards top out at 8 GB. The Socket vs chipset: what decides whether a CPU works guide covers AMD pairing rules.

Memory, PCIe and cooling

Memory support is DDR2-1066 and DDR3-1333 over two channels. Two matched modules feed four cores. ECC works only where the board wires it. Boards with four DIMM slots reach 16 GB with matched kits, while two slot boards top out at 8 GB.

PCI Express slots come from the 7 and 8 series chipset. Chipset video covers office monitors, while a basic card adds outputs.

Cooling follows the 95 W rating with a larger stock heatsink on the shared mount.

Upgrade paths

On Socket AM3 the Phenom II X4 850 can move to Deneb Phenom II parts with 6 MB of L3 on the same board for games and cache heavy work. Memory and storage carry over, and DDR3 DIMMs move to an AM3+ board as well for a later FX step. The locked multiplier fixes all four cores at 3.3 GHz, which keeps behavior steady across office fleets. A slower Propus reference on the same socket is AMD Phenom II X4 840.

A platform move to AM3+ keeps DDR3 while adding FX parts. Keep the AM3 tower for office duty.