VERTEX ATI Radeon HD6950 2048MB DDR5/256bit DVI/HDMI/DP PCI-E (8 Installation problem

[Adicheck]

Hi guys
Would need your expertise and help.
I bought a new graphic card (see above)
Before that I had a Winfast 6800 GTS.
Now today I tried to install the new card.
Started with removing the drivers and software, then I removed the cover the old card the power supply cable and did insert the new card.
What did confuse me right from the start was that the new card had 2 modular cable slots, where the old one had just one.
Problem is I only have one. Did contact the shop they said to try it out as it could work just fine (one cable from Tagan 530W connected to the new card).
Well I started my computer and 1 semi-long beep followed by 2 short beeps did bid me welcome. I thought let me see if the card fits in the PCI E slot...well it did.
Just to be sure I´m asking you guys - will attaching a second modular cable from my Tagan to Vertex Sapphire solve the problem? Or is it something else I did wrong? Just it´s easier to get a second cable if it´s all about it, than running to a shop and get it serviced.

Thanks for for your help

Here are some links
Radeon
http://sklep.sferis.pl/produkt/31875...-800-5000.html
Tagan
http://zasilacze.info/produkty.php?i...tegoria_id=338

P.S.
I do not have the remaining cables from my Tagan - they simply vanished while I moved out.