OEM lock-in can be a problem with OEM systems like Dell, motherboards and power supplies can definitely be custom and not off-the-shelf replaceable. I think the general consensus is once an old BI OEM system dies, you can just buy another used OEM system that's a few generations newer. Since your 7th gen isn't very old yet, I would price both options before making a decision, it's entirely possible it will be cheaper to order another complete used OEM business unit and ebay the spare parts.