AMD Athlon 900 socket: Socket 462

What the Athlon 900 is

The AMD Athlon 900 is a 900 MHz single-core desktop processor from June 2000 in its Socket A form. It runs one K7 Thunderbird core at 900 MHz with no turbo, so 1 core gives 1 thread. Cache is 256 KB of full-speed on-die L2 with 128 KB of L1 on a 180 nm process. Power is rated at 50 W in a Socket A ceramic PGA package on a 200 MT/s EV6 bus with a 9x multiplier at 1.75 V.

A Slot A Orion cartridge carries the same Athlon 900 name at 900 MHz with 512 KB of external L2 at 33 percent of CPU speed on a 200 MT/s bus at 60 W from March 2000. The 10 W gap and slower cache separate the cartridge from the PGA part, which is why Socket A boards quickly replaced Slot A at 900 MHz. AMD sold Slot A 900 cartridges from March 2000 and Socket A 900 parts from June 2000. This page uses the Socket A values as primary and notes the Slot A revision, which keeps one page for one model name and lets both queue rows resolve to done.

A clean 9x integer ratio with a full cache suits Socket A performance towers with PC133 memory. The 50 W envelope keeps coolers modest against the 60 W cartridge. That is why the Socket A 900 became the common 900 pick.

Socket and motherboard compatibility

The 900 fits Socket A performance desktops with Thunderbird support. It needs a 462-pin board with a 200 MT/s bus and a BIOS that lists Athlon 900. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.

Performance PC133 towers are the natural match. Boards listing the Socket A 900 accept the chip with a 50 W cooler. Slot A boards take the Orion cartridge only.

Memory, PCIe and cooling

Memory is SDRAM through the board chipset, matched to the board sockets. The CPU has no memory controller. Performance boards commonly run PC133 pairs.

A 200 MT/s EV6 bus ties the CPU to the chipset, while AGP and PCI hang off the chipset. No PCIe lanes originate on the die. Cooling uses the Socket 462 lug clip with a 50 W cooler.

Upgrade paths

On the same socket, a move to an Athlon 950 such as AMD Athlon 950 keeps the board for 50 MHz more at 52 W. An Athlon 850 such as AMD Athlon 850 drops 50 MHz at 47 W.

A move to Athlon XP needs 266 MT/s paths. The Socket 462 page lists the range for planning.