No, they don't. 2950 (Intel-powered) requires Fully-Buffered ECC DIMMs.2970 (AMD-powered) requires Registered ECC DIMMs. They are not compatible and will not fit in the others' slots. Both are spec'd for 667MHz speeds, max 8x8GB or 8x4GB, depending on the revision.
Does the 2950 and 2970 accept the same memory? 
2950 and 2970 memory