Hi

AI says AYE

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Yes — for the same chassis type (Tower↔Tower, SFF↔SFF, or Micro↔Micro), the OptiPlex 3070 and 5070 motherboards use the same CPU heatsink mounting pattern, so the heatsink mounting holes line up and the cooler is interchangeable between them. dell+2

Why they match

• Dell kept the 3070/5070/7070 generation on a common chassis and thermal design within each form factor. The service manuals for both 3070 and 5070 show identical heatsink removal/install steps: four captive M3 screws in the same numbered sequence on the board. dell+1

• Community and parts listings treat 3070/5070/7060/7070 heatsink/fan assemblies as cross‑compatible within the same form factor (e.g., “for Dell OptiPlex 5070 … 3070 … Micro MFF”), which only makes sense if the mounting holes and socket layout are the same. newegg

• The main differences between 3070 and 5070 are chipset, I/O, RAM slots, and some ports — not the CPU socket or heatsink standoff locations.hardware-corner

Important caveats

• Match form factors:

  • Tower (MT) 3070 ↔ Tower 5070: OK

  • SFF 3070 ↔ SFF 5070: OK

  • Micro (MFF) 3070 ↔ Micro 5070: OK
    Do not mix chassis types (e.g., SFF heatsink onto a Tower board) — the brackets and clearances differ.hardware-corner

• TDP rating: Both generations support 35 W and 65 W CPU options; Dell uses 3‑screw mounts for 35 W and 4‑screw for 65 W. Ensure the heatsink you’re using matches the CPU TDP you plan to run. dell

• Fan header/pinout: In practice these are the same across 3070/5070 in the same chassis, but after swapping boards, verify the fan spins and BIOS doesn’t report a fan error.

swapping 3070 SFF motherboard for 5070 SFF （$35） seems most economical to upgrade gpu than obtaing U1 FlEX psu ($100+).

Likewise all other Dell 30#0 SFF gpu upgrade path including swapping to same class 50#0 SFF board for low cost upgrade to support dual slot width low profile gpu.