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[ The PC Guide | Troubleshooting and Repair Guide | The Troubleshooting Expert | Troubleshooting Specific Components | Troubleshooting the System Memory | Performance Issues ]

I added more memory to the system and performance got worse!

Explanation: Additional system memory was added to the PC, but performance actually decreased.

Diagnosis: There are three common causes of this problem. One is misconfiguring the new memory so that it isn't being used properly. Another is adding slower memory to an existing system than what is already in it, which can cause the memory subsystem to slow down slightly. Adding more memory than can be cached by the secondary cache can also lead to a significant performance hit.


  • Make sure that all of the memory is being recognized in the system. If it isn't, then the upgrade isn't working properly.
  • Double-check the setup of the new memory to make sure that it is configured correctly. Check the BIOS settings, because some BIOSes need settings changed when the memory size changes.
  • If you have added enough memory to take you over 64 MB of RAM, say to 80 MB or higher, your problem may be that your secondary cache can only cache the first 64 MB of memory. The Intel 430FX, 430VX and 430TX chipsets only cache up to 64 MB of RAM. Any memory above that is uncached, and accesses to those memory locations will be much slower than accesses to memory below the 64 MB barrier; see here for more. There is nothing you can do unless you want to upgrade your motherboard.
  • If you have added memory to the system that is either slower in speed than what was there before (70 ns vs. 60 ns for example) or uses a slower memory technology (adding FPM memory to a system using EDO already) then your motherboard may slow down all memory accesses to match the speed of the slower memory, especially if it sets memory timing by autodetecting the memory speed. This will cause a small performance decrease. You may be able to change BIOS settings to get around this.
  • Read this section also, which describes why system performance doesn't generally increase when memory is upgraded.

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