Clocks
Overview
A, A+, AB, B, B', C, C', D, D' chassis
Clock generation differs between Motherboards. It is based around one or two "DRCG-lite" (DRCG = Direct Rambus Clock Generator) clockgen ICs by varying manufacturers (Cypress CY2212 or TI CDCR61A).
All of these boards have an DRCG-lite IC which has an 18.432 Mhz XTAL connected to it's inputs. This DRCG-lite is set for a multiplier of 64/3 and thus creates a 393.216 Mhz clock.
Additionally, all boards (GH-001, GH-003, GH-005, GH-007, GH-012, GH-014, GH-016) that have the original GS (with metal heat spreader, CXD2934GB) have an DRCG-lite IC (also with an 18.432 Mhz XTAL) which is set to a multiplier of 16 to generate a 294.912 Mhz clock for GS. This additional DRCG is not found on their same-chassis-counterparts (GH-004, GH-006, GH-008, GH-010, GH-013) that use the second revision GS (CXD2944GB).
F, G, H chassis
Based around one "DRCG-lite" and one "GMCG" (=Graphics Media Clock Generator) clock generator. The GMCG has a 18.432 Mhz XTAL and generates both, a 54 Mhz or 53.9 Mhz (selectable) clock and also creates a 18.432 Mhz input clock for the DRCG-lite. The DRCG-lite is set for a multiplier of 64/3 and thus creates a 393.216 Mhz clock.
I, J, K, L, M chassis
Based around one single DRCG-lite compatible clock generator with an 18.432 Mhz XTAL, generating a 393.216 Mhz clock, which additionally also generates the selectable 54 Mhz or 53.9 Mhz clock (e.g. Cypress CY22313).