It is HDT, was saying that couple days back in the GTX 4xx discussion, but no-one found it interesting?
http://forums.techpowerup.com/showpost.php?p=1789239&postcount=1792
Anyhow, GTX 280 had seven (7) heatpipes, this one has at least those 5. I'll link a picture here from accelero thread in a moment. edit: 4th picture here gives an idea where rest of the pipes go:
http://forums.techpowerup.com/showpost.php?p=1282201&postcount=11
Compare the base to my avatar and just think NVIDIA-amount of TIM on top of it and that is what you get. They like to slap it a lot!
Also the suction force is massive with the IHS and you can't rotate, so you end with some paste 'ripped' upwards.
Looks like 5 bare heatpipes to me. Glad graphics cards are finally starting move to having the heatpipes directly on the chip like high end CPU heatsinks have been doing for years now.
Both AMD and Intel have IHS in their CPU making direct touch more usable. Only NVIDIA has GPU IHS and only GT200 series and Fermi. You have 5 pipes you need 5 pipes area to cool, bare core would only touch about 3.
Yes, it does use a design like HDT. I wish they used high end TIM like MX-3 though.
The stock NVIDIA paste isn't that bad, they just use too much of it
But now it actually works in this case, as the extra paste fills the heatpipe sidewall holes and doesn't need any fancy to the pipes application that would add cost.