64GB - 8x8GB Speicher RAM Upgrade Apple Mac Pro 3.1 2008 667MHz PC2-5300 Server HS
Your mac has 8 ram slots and the maximum upgrade is 64GB (8x8GB). The standard ram speed for any 2008 Mac Pro is 800MHz, these rams are compatiblehowever you would need to remove any 800Mhz ram installed.