How do we know its a 970?
They just show the underside
But ... the pictures show what looks like a interstitial pin grid array. This can be socketed.
In another picture (search IBM pictures for 970) they have a top picture of a CBGA or ceramic ball grid array. CBGAs are for directly mounting to a board.
The CBGA version would likely go into something like a module or laptop motherboard.
The Interstitial PGA would likely go into a motherboard like a PowerMac. A Intel P4 in a typical motherboard is a IPGA.
And to start a rumor, this a rumor site
, perhaps they don't show the top side with the text because it has the letters 'A' 'P' 'P' 'L' 'E' on it.