One option was the Tyan Thunder S2895A2NRF (image from NewEgg)
|K8WE Dual Core Opteron DDR400 SATAII Audio GbE LAN IEEE1394a USB2.0|
Specs: Dual CPU, Single/Dual Core Opteron (Socket 940) 800Mhz HT, North Bridge: NVidia 2200 and 2050 as well as an AMD8131 memory controller. 8x184 pins DDR 400 PC3200 (Total 16 Gb ECC/REG RAM). 1xPCI, 2xPCI-X 100Mhz,1xPCI-X 133Mhz and 2xPCI Express x16 for NVidia SLI. 1xATA, 4xSATA 3Gbps, RAID0+1+10.Dual Gbps ethernet ports. 4xUSB2.0
That's a "Dual CPU Dual Core|" with 16 GB and SLI support. My current board has 16GB, a single hex-core CPU and two more SATA ports. Oh, and it has DDR3 and 2xUSB3.
That is an impressive rig even by todays standards. That motherboard was from 2007. The rig would be about 2300 USD. (2007 rating). That's excluding PSU, case, mouse and keyboard! The current rig I have was about 1300 USD (2012 rating).
I was going to populate it with two Opteron 225 (Single Core, the Dual Core was too expensive), two 7900GT's and 8x1GB of DDR400 RAM. Which would probably just give me 4GB since it was probably arranged so each core was linked to a bank.
The other was a Tyan Thunder S2882UG3NR (image also from NewEgg)