Buy the ARP T-Shirt! BIOS Optimization Guide Money Savers!
 
   
Workstation & Server CPU Comparison Guide Rev. 7.2
If you have no idea what's different between an AMD Opteron processor and an Intel Co... Read here
BIOS Option Of The Week - AGP Comp. Driving
Since 1999, we have been developing the BIOS Optimization Guide, affectionately known... Read here
   
   
Buy The BOG Book Subscribe To The BOG! Latest Money Savers!

DRAM Ratio (CPU:DRAM)

Common Options : 1:1, 3:2, 3:4, 4:5, 5:4

Quick Review

The choice of options in this BIOS feature depends entirely on the setting of the DRAM Ratio H/W Strap or N/B Strap CPU As BIOS feature.

When DRAM Ratio H/W Strap has been set to Low, the available options are 1:1 and 3:4.

When DRAM Ratio H/W Strap has been set to High, the available options are 1:1 and 4:5.

When N/B Strap CPU As has been set to PSB800, the available options are 1:1, 3.2 and 5:4.

When N/B Strap CPU As has been set to PSB533, the available options are 1:1 and 4:5.

When N/B Strap CPU As has been set to PSB400, the only available option is 3:4.

The options of 1:1, 3:2, 3:4 and 4:5 refer to the available CPU-to-DRAM (or CPU:DRAM) ratios.

Please note that while the Pentium 4 processor is said to have a 400 MHz or 533 MHz or 800 MHz FSB (front side bus), the front side bus (also known as CPU bus) is actually only running at 100 MHz or 133 MHz or 200 MHz respectively. This is because the Pentium 4 bus is a Quad Data Rate or QDR bus which transfers four times as much data as a single data rate bus.

For marketing reasons, the Pentium 4 bus is labeled as running at 400 MHz or 533 MHz or 800 MHz when it is actually running at only 100 MHz, 133 MHz and 200 MHz respectively. It is important to keep this in mind when setting this BIOS feature.

For example, if you set a 3:2 ratio with a 200 MHz (800 MHz QDR) CPU bus, the memory bus will run at (200 MHz / 3) x 2 = 133 MHz or 266 MHz DDR.

By default, this BIOS feature is set to By SPD. This allows the chipset to query the SPD (Serial Presence Detect) chip on every memory module and use the appropriate ratio.

It is recommended that you select the ratio that allows you to maximize your memory modules' capabilities. But bear in mind that synchronous operation using the 1:1 ratio is also highly desirable as it allows a high throughput.

 

Support Tech ARP!

If you like our work, you can help support out work by visiting our sponsors, participate in the Tech ARP Forums, or even donate to our fund. Any help you can render is greatly appreciated!


If you like to know more about this and other BIOS settings, why not subscribe to the full BIOS Optimization Guide?
Click here to find out how you can do that now!


Links: Discuss BIOS options here in our forums | Back to the list of BIOS options

 
 


Copyright © Tech ARP.com. All rights reserved.