Basically you want to know ... "Which motherboard has dual sockets and are compatible with a quad-core processor?"
Usually there are total 43 motherboards that support quad-core processors to date however in case you want dual socket motherboard, you would want to go for a server class motherboard. Though there are several motherboards in server class that come with dual socket quad-core support however you should go and look for their details in Intel Product Quick Reference Matrix Q2, 2008 and under the Intel Server Boards, look up its first 3 pages for dual socket quad-core supported motherboards that are:
All these have dual socket and a support for multi-core Xeon processors that includes quad-core processor lest you are wondering Xeons, I must also mention that for a server you will be using Xeon processor here and since it's multi-core, it implies quad-core Xeon is included unless otherwise.
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