10 NICs in 1U box - possible?
Solution 1:
This is an easy one for a change! there's loads of 4-port PCIe NICs available - literally google '4 port NIC'. I'm not aware of there being >4-port ones but obviously two of them plus any built-in LOM/mLOMs will give you enough.
Any modern OS will support this without a problem - though you might wish to rename the ports once they're up so you know which is which :)
Oh and finally why not just have multiple virtual NICs off one port, either via VLAN tagging or just as separate MACs/IPs?