[ The PC Guide | Systems and Components Reference Guide | System Memory | Memory Size ]

Maximum Cacheable Memory

It is extremely important to realize that many PCs will not allow all of the memory they support to be cached. For example, Intel's popular 430xx series of chipsets includes 4 different variants: the 430FX, 430VX, 430HX and 430TX. Of these, all but one (the 430HX) will support 128 MB of maximum system memory, but will only allow 64 MB of this to be cached (the 430TX actually allows 256 MB of total memory, but only 64 MB is cacheable). Any memory used above 64 MB cannot be cached by the level 2 cache.

Using more system memory than can be cached can lead to significant performance degradation, depending on how fast the underlying memory itself is (if you are using slower memory you take more of a hit when that memory cannot be cached than if you are using faster memory like SDRAM). This subject is described in detail in the section discussing the secondary cache.

Next: Real and Virtual Memory

Home  -  Search  -  Topics  -  Up