A cryocooled system with I/O interface circuits, which enables high-speed system operation of superconductive single-flux-quantum (SFQ) circuits at over 40GHz, and the demonstration of a 47-Gbps SFQ 2×2 switch system are presented. The cryocooled system has 32 I/Os and cools an SFQ multi-chip module (MCM) to 4K with a two-stage 1W Gifford-McMahon cryocooler. An SFQ 4:1 multiplexer (MUX) and an SFQ 1:4 demultiplexer (DEMUX) have been designed to interface the speed gap between the I/O (-10Gbps/ch) and SFQ circuits (>40GHz). An SFQ 2×2 switch chip, in which the MUX/DEMUX and an SFQ 2×2 switch are integrated, and an 8-channel superconductive voltage driver (SVD) chip have been designed with an advanced cell library for a junction critical current density of 10kA/cm². An SFQ 2×2 switch MCM has been made by flip-chip bonding the switch chip and SVD chip on a superconductive MCM carrier with ∅50-μm InSn solder bumps. An SFQ 2×2 switch system, which is the switch MCM packaged in the cryocooled system, has been demonstrated up to a port speed of 47Gbps for the first time.