TH7-II, Questions about settings in BIOS

HI,
Do you disable or enable these?

System BIOS Cacheable
Video BIOS Cacheable
Video RAM Cacheable

thanks for info

..in lack of better expert opinion I can say from my own experience: disable them all and you'll be better off.. ..bios shadows tend to cast shadow over system stability.. (OMG, really slow day at work today it seems to be when I have time for sucha high quality poetry.. )

I just leave them where they default. I figure Abit knows best.

Thats one for enable, and one for disable. What do the rest of you think?

Disable every other one?


Just kidding,
Eggroll

According to the BIOS guide at rojakpot.com and various tweaknig programs, you should disable them all. They are there for compatibility with VERY old hardware, and do more harm than good (e.g. they occupy memory). I have had them all disabled for years, without problems.

Duster,

This is an excerpt from Adrian's Rojak Pot "Definitive BIOS Optimization Guide" found here:

http://www.itcp.net/~awsh/Speed_Demonz/BIOS_Guide/BIOS_Guide_Index.htm


It says:

"System BIOS Cacheable

Options : Enabled, Disabled

This feature is only valid when the system BIOS is shadowed. It enables or disables the caching of the system BIOS ROM at F0000h-FFFFFh via the L2 cache. This greatly speeds up accesses to the system BIOS. However, this does not translate into better system performance because the OS does not need to access the system BIOS much.

As such, it would be a waste of L2 cache bandwidth to cache the system BIOS instead of data that are more critical to the system's performance. In addition, if any program writes into this memory area, it will result in a system crash. So, it is recommended that you disable System BIOS Cacheable for optimal system performance.

     

Video BIOS Cacheable

Options : Enabled, Disabled

This feature is only valid when the video BIOS is shadowed. It enables or disables the caching of the video BIOS ROM at C0000h-C7FFFh via the L2 cache. This greatly speeds up accesses to the video BIOS. However, this does not translate into better system performance because the OS bypasses the BIOS using the graphics driver to access the video card's hardware directly.

As such, it would be a waste of L2 cache bandwidth to cache the video BIOS instead of data that are more critical to the system's performance. In addition, if any program writes into this memory area, it will result in a system crash. So, it is recommended that you disable Video BIOS Cacheable for optimal system performance.

     

Video RAM Cacheable

Options : Enabled, Disabled

This feature enables or disables the caching of the video RAM at A0000h-AFFFFh via the L2 cache. This is supposed to speed up accesses to the video RAM. However, this does not translate into better system performance.

Many graphics cards now have a RAM bandwidth of 5.3GB/s (128bit x 166MHz DDR) and that number is climbing constantly. Meanwhile, SDRAM's bandwidth is still stuck around 0.8GB/s (64bit x 100MHz) or at most 1.06GB/s (64bit x 133MHz) if you are using a PC133 system.

Now, although a Pentium !!! 650 may have a L2 cache bandwidth of about 20.8GB/s (256bit x 650MHz), it makes more sense to cache the really slow system SDRAM instead of the graphics card's RAM.

Also note that caching the video RAM doesn't make much sense even with the Pentium !!!'s high L2 cache bandwidth. This is because the video RAM communicates with the L2 cache via the AGP bus which has a maximum bandwidth of only 1.06GB/s using the AGP4X protocol. Actually, that bandwidth is halved in the case of the L2 cache caching the graphics card's RAM because data has to pass in two directions.

In addition, if any program writes into this memory area, it will result in a system crash. So, there's very little benefit in caching the video card's RAM. It would be much better to use the processor's L2 cache to cache the system SDRAM instead. It is recommended that you disable Video RAM Cacheable for optimal system performance."


You can peruse this site which seems to support BIOS shadowing and enabling the cacheable settings:

http://www.pcguide.com/ref/mbsys/bios/set/advchSystem-c.html
http://www.pcguide.com/ref/ram/logic_Shadowing.htm

And this one that seems to be on the disabling side of the fence:

http://www.lostcircuits.com/advice/bios2/12.shtml

Based on scanning these I tend to support the disablers because it sounds like shadowing the BIOS can cause conflicts by write-protecting memory that might be in use by other components. And, even though accessing BIOS code would be faster from RAM than the ROM, there doesn't appear to be any such access after boot-up, or if there is, it's so minimal that it seems a performance gain would be minimal as well.

You can always experiment. It seems the thing to watch out for if you do shadow the BIOS is to make sure the memory that gets used to shadow the BIOS isn't in use by something else.


Hope this helps.

Peace,
Eggroll

Thanks Eggroll very informative was woundering this myself. The ABIT manual says to use sys bios & vidio bios cacheable but my vidio card says not to, I have had them enabled for the last month with no prob but I think I will change them now.

Set em all OFF.

System is faster for it,...especially if u are GeForce Powered

Thanks Guys.

no probs, glad to oblige!