Intel AIMB-253 Dram Timing Selectable, CAS Latency Time, Dram RAS# to CAS# Delay, VGA Setting

DRAM Timing Selectable

Selects whether DRAM timing is controlled by the SPD (Serial Presence Detect) EEPROM on the DRAM module. Setting to [By SPD] enables DRAM timing to be determined automatically by BIOS based on the con- figurations on the SPD. Selecting [Manual] allows users to configure the following fields manually.

CAS Latency Time

This controls the timing delay (in clock cycles) before SDRAM starts a read command after receiving it. Smaller clocks increase system perfor- mance while bigger clocks provide more stable system performance.

DRAM RAS# to CAS# Delay

This field allows you to set the number of cycles for a timing delay between the CAS and RAS strobe signals, used when DRAM is written to, read from or refreshed. Fast speed offers faster performance while slow speed offers more stable performance.

DRAM RAS# Precharge

This item controls the number of cycles for Row Address Strobe (RAS) to be allowed to precharge. If insufficient time is allowed for the RAS to accumulate its charge before DRAM refresh, refresh may be incomplete and DRAM may fail to retain data. This item applies only when synchro- nous DRAM is installed in the system.

Precharge Delay (tRAS)

The field specifies the idle cycles before precharging an idle bank.

System Memory Frequency

Use this item to configure the clock frequency of the installed DRAMs.

**VGA Setting**

The following items allow you to configure the VGA settings of the sys- tem.

PEG/Onchip VGA Control

This setting allows you to select whether to use the onchip graphics pro- cessor or the PCI Express card.

When set to [Onchip VGA], the motherboard boots up using the onboard graphics processor, even when a PCI Express graphics card is installed.

When set to [PEG Port], the motherboard boots up using the PCI Express graphics card, if one is installed. Otherwise, it defaults to the onboard graphics processor.

AIMB-253 User Manual 38