You can easily get dual (possibly quad?)-cpu AMD mobo's and add to the power. It's the server line you'd use but same basic technology. $500 USD would get you

You can easily get dual (possibly quad?)-cpu AMD mobo's and add to the power. It's the server line you'd use but same basic technology. $500 USD would get you a single Phenom 940 with 8GB of ECC ram, computers are cheap these days.