I don't see why not, as long as you can deal with the fact that the clock speeds on server parts are going to be lower and the fact than no game will be optimized for the ridiculous number of threads( or the fact that there are 2 processors), if your using Xeons, the bigger faster cache might give you a boost. So sure you can do it
I know the clock speeds are going to be crap and that games wont be able to use all of the threads, but it could act as a portable build too, running game servers for LAN parties and other things, right?
Yes they can. The many issue that I ran across was actually memory latency. As the older dual/quad socket chipsets required the use of ECC. The increased delay on memory caused some odd texture popping and some other oddities that are hard to explain.
As Kiaxa mentions the lower clock speeds maybe your main issue. But it should be fine if say using something higher than 2Ghz on the Core2 based Xeons.
Portable might be pushing it, most dual socket motherboards are SSI EEB which is a stupidly large form factor (12" x 13"). But if you are planning to also use it as a power server as well it should do the job well. You also need to know that getting into dual socket servers is going to be very expensive and you should be absolutely sure you know what you want to do with it so you don't waste your money. That being said a dual Xeon server will do just about anything you want it to really well
Cases that can house a dual cpu mobo are huge and heavy,not easy to move around.Though there are some cases with wheels (Lian-Li PC-V2120) or handles (CM Cosmos II)
Server builds are all about throughput since the parts are expensive.Set a budget and get the best performing parts within that budget.
For a performance benchmark a beige horizontal case with pentium 3 processor and 512mb of ram houses the Domain Controller of the company i work for and it has been running flawlessly since 2002.We have about 150 employees.You might not need a 2 cpu build for a storage/domain control server.