I just share you my experience in the past with triple monitors, dunno if this help help you.
Back then, I was struggling looking for a way to let my HD5770 to run multiple monitor while all of my monitors were only support VGA. They said, one of my monitor SHOULD has a HDMI/DP which are digital input/output, unlike VGA/DVI which are analog (DVI is hybrid, still, not pure digital) to work. To make it happen in my current condition, I must have an ACTIVE DP to DVI/VGA converter so my 3rd monitor can act as extension, not a clone. Well, the rest was a long story and I forgot where did I wrote that topic. So, the conclusion based on above regarding how to work with triple monitors are :
1. Your card must support one of HDMI or DP
2. Your monitor input should consist of 2 analog and 1 digital. If all of them analog, you must buy an active digital to analog converter (DP -> DVI/VGA)
Now back to topic, this Sapphire Vid 2x has DP input, while your card doesn't even has HDMI or DP. It doesn't matter the outputs are. So I think, your setup is not possible. My better suggestion for you, save your money, sell your card quickly, buy newer card. Did you know, GT9800 was already obsolete and are easily overrun by newer $130 cards in term of performance, technology (shader model, DirectX), and power consumption ? If I own a 9800, I still could sell it for around $100
And please, triple monitor using obsolete graphics for GAMING ? no!