# Write Back or Write Through?



## Derek895 (Feb 17, 2005)

I have seen the BIOS option for either write-back or write-through in connection with the CPU cache on some laptops. Could someone explain these terms and which to select?

Thanks

Derek


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## UncleMacro (Jan 26, 2005)

When a CPU tries to store a value at a memory address there are two ways to deal with it: it can just write the value to the cache (write-back), or it can write the value to both the cache and to memory (write-through). Write-back is quicker because it eliminates unnecessary writes to memory. The fact that the cache and memory are out of sync doesn't matter because the memory controller knows to write the cache value out before something outside of the CPU tries to read it directly from memory. Just set it to write-back and forget it.


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## Derek895 (Feb 17, 2005)

Thanks for explaining


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