Useful Tips

System BIOS Cacheable


Shading is the transfer to the RAM of the BIOS contents of all kinds of expansion cards that have it. Since access to RAM requires much less time than accessing directly to the BIOS of the card, data exchange with such a card is faster.

Option Location - Item BIOS FEATURES SETUP (AWARD BIOS 4.51PG and AMIBIOS1.24), Advanced (AWARD BIOS 6.0), Advanced BIOS Features (AWARD BIOS 6.0PG and AMIBIOS 1.45).

Video BIOS Shadow (Video ROM BIOS Shadow) - determines whether it is necessary to copy the contents of the BIOS of the video card to the faster RAM of the computer. Since during such copying the speed of the video card increases, it is advisable to enable this option (Enabled).

System BIOS Shadow - determines whether to copy the contents of the BIOS of the computer to RAM. The recommendations are the same. But since the BIOS is practically not used by modern operating systems, it is recommended to turn this option off (Disabled).

The same applies to caching options: System BIOS Cacheable and Video BIOS Cacheable.

Principle of operation

One of the most important functions of the BIOS, as you know, is to provide access from application programs to various computer devices. For this purpose, specialized software is stored in the BIOS.

Access to data contained in read-only memory is not as fast as access to information contained in the processor cache. Therefore, BIOS caching can significantly reduce the processor access time to the data contained in the BIOS and, thus, improve system performance. BIOS caching is available on most modern motherboards.

If you enable the BIOS caching function, then during boot of the computer information from the address range F0000h-FFFFFh BIOS ROM will be transferred to ultra-fast random access memory - the cache of the second level of the central processor. Since the volume of the second-level cache is much larger than the volume of the BIOS ROM, then all the necessary information will easily fit in it.

Should I enable the option?

Despite the fact that transferring BIOS ROM data to the cache sometimes helps to speed up and facilitate the access of the processor to the necessary information from the BIOS, nevertheless, in most cases, the usefulness of the System BIOS Cacheable function is limited.

The thing is that modern operating systems, such as Windows XP and newer, do not use the built-in BIOS tools to access computer devices, but use the drivers installed in the operating system for this purpose.

In addition, it should be borne in mind that the data from the BIOS will occupy some space in the cache, which can adversely affect the performance of the processor itself, as well as lead to system malfunctions.

Therefore, if you enable BIOS caching and use modern operating systems, such as Windows XP, Vista, 7 and 8, then most likely this data will not be required by the operating system, but will be dead weight in the cache.

However, in older operating systems, such as MS-DOS, as well as, in part, and Windows 95, built-in BIOS tools are usually used to access devices. If you have any of these OSs installed on your computer, then BIOS caching can often be justified, as it will improve system performance.

Based on the foregoing, it is recommended to turn off the BIOS caching of the computer by setting the Disabled option if you are using Windows XP and newer operating systems, and enable BIOS caching by setting the Enabled option if you are using intensive BIOS-based operating systems systems like MS-DOS.

In addition, it is highly recommended that you disable the BIOS caching option if you are updating the BIOS contents (flashing). If you perform BIOS firmware with the caching option turned on, this can lead to incomplete firmware flashing of the BIOS, and, as a result, to the inoperability of the personal computer.

Method 1: Award BIOS

If Phoenix / Award firmware is installed on your system board, the action algorithm will look something like the following. Remember that parameter names may vary slightly.

  1. We reboot the PC. We enter BIOS with the help of a service key or a key combination. They are different depending on the model and version of the hardware: Del, Esc, F2 and so on.
  2. Push combination Ctrl + F1 to enter advanced settings. On the page that opens, go to MB Intelligent Tweaker (M.I.T.) and click Enter.

You can carefully increase the voltage supplied to the RAM, but not more than 0.15 volts.

We return to the main BIOS page and select the parameter Advanced Chipset Features.

Settings are finished. We exit the BIOS with the changes saved and run any special test to verify the stability of the system and RAM, for example, in AIDA64.

  • If you are not satisfied with the results of the RAM settings, repeat according to the above algorithm.
  • Method 2: AMI BIOS

    If the BIOS on your computer is from American Megatrends, then there will not be radically significant differences from the Award. But just in case, we briefly consider this case.

      We enter the BIOS, in the main menu we need the item "Advanced BIOS Features".

  • We leave the BIOS and run the benchmark to verify the correctness of our actions. We do a cycle several times until the best result is achieved.
  • Method 3: UEFI BIOS

    Most modern motherboards have a UEFI BIOS with a beautiful and convenient interface, support for the Russian language and a computer mouse. The possibilities for setting up RAM in such firmware are very wide. Let's consider them in detail.

      We go into the BIOS by clicking Del or F2. Other service keys are less common, you can find them in the documentation or from the prompt at the bottom of the screen. Next, go to "Advanced Mode"by clicking F7.

    On the advanced settings page, go to the tab "Ai Tweaker"we find the parameter "Memory Frequency" and in the pop-up window, select the desired clock speed of RAM.

    Moving down the menu, we see the line “DRAM Timing Control” and clicking on it, we get into the section for adjusting various RAM timings. By default, all fields are set to "Auto"but if you wish, you can try to set your own response time values.

    Go back to the menu "Ai Tweaker" and go to “DRAM Driving Control”. Here you can try to slightly increase the frequency factors of RAM and speed up its work. But this must be done consciously and carefully.

    Again we return to the previous tab and then we observe the parameter "DRAM Voltage"where it is possible to change the voltage supplied to the memory modules of the electric current. You can increase the voltage by the minimum values ​​and in stages.

    Then we go to the advanced settings window and move to the tab "Advanced". We visit there "North Bridge", motherboard northbridge page.

    Here we are interested in the line "Memory Configuration"which we click on.

    In the next window, you can change the configuration parameters of the RAM modules installed in the PC. For example, enable or disable the control and error correction (ECC) RAM, determine the interleaving mode of banks of RAM and so on.

  • After completing the settings, we save the changes made, leave the BIOS and boot the system, check the RAM in any specialized test. We draw conclusions, correct errors by re-adjusting the parameters.
  • As you saw, setting up RAM in BIOS is quite possible for an experienced user. In principle, in case of your incorrect actions in this direction, the computer simply will not turn on or the firmware itself will reset the erroneous values. But caution and a sense of proportion will not hurt. And remember that the wear of RAM modules at increased rates is correspondingly accelerated.

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