Also called CG14 (for Color Graphics, number fourteen), and occasionally spam in some older documentation, the SX is the name given by Sun Microsystems to the graphics card fitted to the motherboard of the SPARCstation 20. It is a 2D-only card, capable of high resolution in 24-bit color, with hardware acceleration. Unusually for an onboard device, it required the installation of a video SIMM (VSIMM) into one of the SPARCstation 20's RAM slots, which contained the interface logic, the accelerator chip, and either 4 or 8 MB of framebuffer RAM. The SS20 featured 2 such RAM slots, and could in fact take 2 VSIMMs - but to take advantage of the second VSIMM, an inexpensive SBus card containing a 13W3 connector and a RAMDAC chip was required.
The SX is supported under Linux, Solaris, OpenBSD, NeXTSTEP and OPENSTEP. NetBSD supports it, but without acceleration. It provides 24-bit color output at either 1152x900 with a 4MB VSIMM, or 1280x1024 with additional pixmap cache with an 8MB VSIMM. Unlike most PC graphics accelerators, it's not possible to trade color depth for resolution or vice versa.
There also exists a variant of the SPARCstation 10, referred to as the SPARCstation 10 SX, which has an onboard CG14. Most SS10s seem to have the VSIMM slots, but only the 10SX has the onboard 13W3 connector and DAC. The Sun part numbers for the SS10SX VSIMMs and extender card are different than those for the SS20, but they're physically identical.