The PowerEdge T40 continues Dell's low-cost, compact entry-level server series. Outwardly, this is a small "turret" with characteristic Dell branded design elements, more like a regular PC. Inside, there is a small single-socket entry-level Intel Xeon E board. 
Moreover, the Dell PowerEdge T40 is really a product for business, and not an ordinary PC in a slightly unusual design. Someone will say that the differences here are only in the details, but they are the decisive ones: support for ECC memory, remote (out-of-band) management, a large set of PCI-E slots, 24/7 operation, easy deployment, a host of additional security and diagnostic tools, and finally, enterprise-level technical support.
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Source: 3dnews.ru