Slot 1 was the replacement for Socket 8. Slot 1 has L2 cache embedded into the die of the CPU. It uses a Coppermine core with Advanced Transfer Cache (ATC) for better pipelining. Socket 8 did have L2 cache embedded on the CPU, but it was located on a circuit board outside the core.

The SECC was superseded by the SECC2 in some Pentium II 450s and all Pentium IIIs. The SECC2 supports direct contact with the heatsink allowing a more proficient cooling architecture.

For backward compatibility, a converter card called slotket could be used to contain Socket 8. The slotkets for Socket 8 were rarely used but allowed a Pentium Pro CPU to be utilized in a Slot 1 motherboard. Additionally, there were slotkets for the Socket 370 CPU that could be inserted into Slot 1 which was commonly used. Most of the newer slotkets for the Socket 370 CPU were fitted with a voltage regulator so that the motherboard allowed the device.

Depending on the CPU, various clock rates could be attained:

• Pentium II: 233–450 MHz
• Celeron: 266–433 MHz
• Pentium III: 450–1,133 MHz
• Celeron and Pentium III using slotkets: Up to 1,400 MHz
• VIA Cyrix III using Slotkets: 350–733 MHz
• VIA C4 using Slotkets: 733–1,200 MHz