VIA C3 Processor 1.0A socket: Socket 370

What the C3 Processor 1.0A is

The VIA C3 Processor 1.0A is a 1000 MHz single-core desktop processor from 2002. It runs one Centaur Ezra-T core at 1000 MHz with no turbo, so 1 core gives 1 thread. Cache is 64 KB of L2 with 128 KB of L1 on a 130 nm process. Power is typical near 10 W in a Socket 370 ceramic PGA package on a 100 MHz front side bus with a 10x multiplier at 1.45 V.

The 1.0A reaches 1000 MHz on a slower 100 MHz bus with a high 10x multiplier, which is why it suits boards with 100 MHz SDRAM paths while the plain 1.0 needs a 133 MHz path for the same clocks. VIA sold the 1.0A in 2002 with other Ezra-T parts such as the 933 MHz 933T. The chip supports MMX, 3DNow and LongHaul power saving.

A 1 GHz clock on a 100 MHz bus with a 10 W envelope suits older Socket 370 boards with PC100 memory and basic cooling. The high multiplier keeps board timing relaxed. That is why the 1.0A shipped as a drop-in speed lift for 100 MHz bus systems.

Socket and motherboard compatibility

The 1.0A fits Socket 370 desktops with a 100 MHz bus and Ezra-T support. It needs a 370-pin board with a 100 MHz path and a BIOS that lists VIA C3 Ezra-T parts. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.

Older SDRAM towers with 100 MHz paths are the natural match. Boards listing C3 1.0A accept the chip with a 10 W cooler. Boards set only for 133 MHz operation may still run it, but the bus tables must include the 100 MHz setting.

Memory, PCIe and cooling

Memory is PC100 SDRAM through the board chipset at the 100 MHz bus rate, matched to the board DIMM sockets. The CPU has no memory controller, so the chipset sets the type and speed. Apollo boards commonly run PC100 pairs for 100 MHz Ezra-T parts.

A 100 MHz front side 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 370 lug clip with a cooler rated for 10 W. Standard height blocks clear most SDRAM tower cases.

Upgrade paths

On the same socket, a move to a C3 Processor 1.0 such as VIA C3 Processor 1.0 keeps the chip family while moving to a 133 MHz bus with a 7.5x multiplier when the board supports it. The 1.0 needs the faster bus path, so the board must list 133 MHz operation. A C3 866T such as VIA C3 Processor 866T drops 134 MHz at slightly lower power.

A move to Nehemiah C3 parts adds SSE support on 133 MHz paths with a BIOS update. The Socket 370 page lists the Tualatin to Nehemiah range for planning. Note: the exact month for the Ezra-T 1.0A is not published in the open lists; this page uses year 2002 from the Ezra-T family window.