AMD Duron 850 socket: Socket 462

What the Duron 850 is

The AMD Duron 850 is an 850 MHz single-core desktop processor from January 2001. It runs one K7 Spitfire core at 850 MHz with no turbo, so 1 core gives 1 thread. Cache is 64 KB of full-speed L2 with 128 KB of L1 on a 180 nm process with 25 million transistors. Power is rated near 37 W in a Socket A ceramic PGA package with part number D850AUT1B on a 200 MT/s front side bus with an 8.5x multiplier at 1.6 V.

Spitfire trims Thunderbird L2 from 256 KB to 64 KB at the same 180 nm base, which is why the 850 at 850 MHz trails Athlon 850 parts with full cache in office tasks despite matching clocks. AMD placed the 850 in January 2001 with other Spitfire value parts such as the 800 MHz Duron 800. The chip supports MMX, Enhanced 3DNow and LongHaul concepts on desktop boards.

Low clocks with a small cache and a modest envelope suit early Socket A value towers with SDRAM and AGP graphics. The 1.6 V core keeps cooler cost down in budget cases. That is why the 850 shipped in entry desktops with integrated video.

Socket and motherboard compatibility

The 850 fits Socket A value desktops with Spitfire support. It needs a 462-pin board with a 200 MT/s bus and a BIOS that lists Duron Spitfire parts. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.

Early SDRAM towers with VIA KT133 paths are the natural match. Boards listing Duron 850 accept the chip with a 37 W clip cooler. Later 333 MT/s-only boards with no 200 MT/s tables may refuse the old bus ratio, so the support list decides.

Memory, PCIe and cooling

Memory is SDRAM and DDR through the board chipset, matched to the board DIMM sockets. The CPU has no memory controller, so the chipset sets the type and speed. Early KT133 boards commonly run PC100 and PC133 SDRAM for 200 MT/s Spitfire parts.

A 200 MT/s front side bus ties the CPU to the chipset on a 100 MHz clock, while AGP and PCI hang off the chipset. No PCIe lanes originate on the die. Cooling uses the Socket 462 lug clip with a cooler rated for 37 W. The exposed die needs level mounting pressure with no tilt.

Upgrade paths

On the same socket, a move to a Duron 950 such as AMD Duron 950 keeps the board and memory when the support list names it. The 950 adds 100 MHz at a similar 42 W envelope, so the existing clip cooler often carries over. An Athlon 1333 such as AMD Athlon 1333 adds full 256 KB cache with higher power needs.

A move to Socket 754 needs a new board for on-chip DDR with HyperTransport. The Socket 462 page lists the Spitfire to Barton range for planning.