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The BIOS (Basic Input/Output System)

The BIOS (Basic Input/Output System)
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As you easily can see from my Motherboard Benchmark Results Table , the performance of the motherboard is highly depending on the memory timing you adjust in your BIOS setup. The settings you are able to change and the different values however differ a whole lot from chipset to chipset and from BIOS to BIOS. Some BIOSes hardly leave it up to you to tune up your system, others give you almost too many settings to choose from and some BIOSes adjust the memory timing very well after you only had to choose the DRAM speed. In general you can say that for optimal performance you should keep most of the values as low as possible. Should you choose them too low however you will either occur system crashes/hangs or your system wont boot at all. Even if this should happen there's nothing you'll have to fear though. Just load setup defaults after entering setup again and you can be sure your system will work just fine - just not too fast however. Also there's no long term damage to fear - readjust your settings and everything will be as it was before.

I will not discuss the basics about the BIOS, because there already exists an excellent and extremely comprehensive summary, the BIOS Survival Guide , latest edition 5.1, which is a must read for everybody who isn't already quite experienced with the BIOS setup. If you want to, you can download the whole Guide as a Word document and read it relaxed offline. All the topics discussed in this Guide I wont even touch!

The Settings

You'll find the memory timing settings usually in the Advanced Chipset Setup section of the BIOS setup.

  • Auto Configuration

    • If you ever should want to get the most out of your system then switch this one off - quickly ! You anyway wont be able to change anything unless you do.

  • DRAM Read Timing

    • Short Explanation:
    • Most accesses of the main memory are actually happening as a Burst. This is due to the cache not fetching only one DWord/Word/Byte, but rather than that fetching 4 or 8 consecutive DWords in a line. That's obviously much more effective than getting each Byte on its own into the cache or the CPU. A burst read is done (in easy words) by telling the memory the first address first and then consecutive DWords can be read in a row, without telling the memory each address anymore. This obviously saves time. In clock cycles this looks then like x-y-y-y for a normal burst or x-y-y-y-z-y-y-y for a so called back-to-back burst. For Pipelined Burst Cache RAM e.g. this is 3-1-1-1 or 3-1-1-1-1-1-1-1. That's the amount of clock cycles the CPU needs for reading from its PB cache. Now for the main memory it's not a fixed value like for the PB cache, instead you can and have to adjust the x,y and sometimes also the z, due to the different DRAM types and speeds.

      Now after you've read this and hopefully understood it as well ;-), you see that the system will be faster when the x,y,z values are low rather than high, 'cause it takes the CPU less clock cycles to actually get the data it wants to process.

      The DRAM Read Timing is more or less the 'y' . Therefore you normally can choose from something like x222 and x333 for EDO (which is faster) and x333 and x444 for FPM RAM . You often have to choose it combined which each other, like x222/x333 and x333/x444, where the higher value stands for FPM, the lower for EDO RAM.



    • Recommendation:
    • Choose the lowest possible value and try out your system ! If you don't occur crashes after starting some programs (best under Windows 95 or more sophisticated OSes) it obviously is the right setting for your RAM.

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