What kind of memory for IBM XEON xseries 226 need

First, find out exactly what is in it now.
Google "CPUZ"
Download the zip file and extract it.
Run the program and it will provide the exact speed, size and slot locations of your installed memory modules.
Then contact a major memory vendor such as Crucial.com or Kingston.com
Let them know what you have in your server and they will tell you how to get to 4GB.
One more thing, make sure that you have the absolute latest BIOS installed. BIOS updates frequently include support for faster memory. Get the BIOS from IBM's website. You will need the exact model number. It should be on the front of the case by the serial number.

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