Wonder why, I mean, the copper for those costs like... maybe five dollars a card
The raw materials might be cheap, but copper heatpipes are actually fairly expensive.
Anyways my 5830 only has 3 heatpipes so you should be ok as long as that missing heatpipe isn't one of the ones touching the core.
Not that expensive, considering you can regularly buy a Coolermaster Hyper 212 for $20 shipped from Newegg with four much longer heatpipes, and that includes all the fins, the backplates, mounting hardware, fan, box, and a tube of goop, plus markup for all involved.
I would be surprised if the whole heatsink on that card cost the manufacturer much more than $5.