Power connectors on Radeon HD3870x2

The card needs to be connected with two PCI-E power cords.
The two female connectors on the card are different: one has 6 pins and one
has 8 pins.
The PCI-E cords of my power unit all they have 6+2 pins, i.e. every
connector may be "assembled" to become an 8 pins plug.
The question is about the 8 pins connector: may I use the 6+2 pins cord for
that?
What is the purpose of the additional 2 pins plug?

Tnx in advance.

PS: The documentation in the box of this card is..... inconsistent.

"Pascal" <p.DeleteThis@scal.net> wrote in message
news:47c03981$0$10621$4fafbaef@reader2.news.tin.it...
> The card needs to be connected with two PCI-E power cords.
> The two female connectors on the card are different: one has 6 pins and
> one has 8 pins.
> The PCI-E cords of my power unit all they have 6+2 pins, i.e. every
> connector may be "assembled" to become an 8 pins plug.
> The question is about the 8 pins connector: may I use the 6+2 pins cord
> for that?

Yes. That was the intent of the 6+2 pin cord.

> What is the purpose of the additional 2 pins plug?

As Augustus said, more juice. The current draw of the card exceeds the
[conservatively rated] per-pin capacity of the 6-pin connector, so 2 extra
pins were added.

--
"War is the continuation of politics by other means.
It can therefore be said that politics is war without
bloodshed while war is politics with bloodshed."