i did check my only remaining 630 board, both are indeed NC, however it seems that not all boards leave the leads unconnected. In all 630 compliant machines, harness side those leads are grounded, beginning with the 6360 they provide 3.3v for the PCI slot, but it seems that some of the 630 type LB do have them connected to, uhm something, through R44 and R43. These are not mounted, but if you follow the traces they go through some caps (including C34) and then I lose them towards the RAM slots.
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