ProComp Voodoo2 G111
The ProComp Voodoo2 follows 3Dfx' reference PCB design like many other manufacturers did. However, ProComp did add a heatsink on the 3Dfx Chuck chip to differentiate from the other cards on the market. Basically the Voodoo2 doesn't need a heatsink on stock clockfrequencies but it doesn't hurt to add a heatsink since the Voodoo2 can get quite hot in SLI and poorly ventilated systems.
Back in the day many AT and early ATX systems didn't have extra side ventilation. Ventilation was more focused on the CPU and exiting the case through the power-supply leaving your precious SLI setup uncooled.