ASROCK X299 Extreme4 User Manual page 72

Fourth Timing
RTL (A1)
Configure the round trip latency for channel A1.
RTL (A2)
Configure the round trip latency for channel A2.
RTL (B1)
Configure the round trip latency for channel B1.
RTL (B2)
Configure the round trip latency for channel B2.
RTL (C1)
Configure the round trip latency for channel C1.
RTL (C2)
Configure the round trip latency for channel C2.
RTL (D1)
Configure the round trip latency for channel D1.
RTL (D2)
Configure the round trip latency for channel D2.
IOL (A1)
Configure the IO latency for channel A1.
IOL (A2)
Configure the IO latency for channel A2.
IOL (B1)
Configure the IO latency for channel B1.
IOL (B2)
Configure the IO latency for channel B2.
IOL (C1)
Configure the IO latency for channel C1.
IOL (C2)
Configure the IO latency for channel C2.
66