I have been looking at that system, but I don't have experience with it yet. You definitely can purchase a second VGA Water Block (ZM-GWB2) separately.
My inexperienced opinion (for what it's worth):
I don't see why you couldn't add the second VGA block to the cooling loop. It is only another water block and a short length of tubing, and I don't think the extra volume of coolant it needs will be a big deal for the reservoir or pump. The block is less than an inch tall, too. I do wonder if the tube orientation will want to occupy the same space as the SLI bridge. Hmmm...I'd ask Zalman what they think.
i am plainging to buy the Zalman Reserator 1 Plus i loved the instuctional video on cnet and i was sold.. but i have concerns i have 2 bfg 7800 gtx's sli on a fatil1ty amd socket 939 motherboard.. is there any way i can buy a 2nd water block for my 2nd cards gpu to cool the 2nd one and if so will the Reserator of the product allow it? what do i do
are there any other water kooling kits that might bette suit me?

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