Building water cooling system for 2 GTX 480, any advice?

Res before pump, after that it doesn't matter.
Why 2 different size's of tubing ?

^agreed. Why a MCP655 w/ 3/8" adapter kit? It is native 1/2" ID tubing...you'd want to run this for your entire loop if possible.

^+2. The golden rule is res before pump. After that, moving around the rad,etc will only change the temps 3-8C depending on your heat load, flow rates, rads,etc.

@OP:

Are you planning to upgrade your GPU's at any point? If so, you might consider a universal block like the MCW80 and using RAMsinks for the RAM modules. A full cover block will work fine, but is more costly and won't work on the next series of card (ex. GTX580, etc) For the cost of 1 full cover block, you could almost get 2 MCW80's and the RAMsinks needed to complete that option.

You could also consider the Swiftech full cover 'plates' that go with the MCW80 block. Between the block and plate, you'd pay almost as much as a full cover block, but you can reuse the block and just get a different plate for the next series of card... buy another $45 'plate', or buy another $130 full cover block.

But, if you don't mind the price, full blocks are great; just do some research before you buy...not all perform the same.

^ Good point.

Just thought I'd offer up some alternatives if the OP decided to get different hardware in the future...which is what a large percentage of all of us do...

RES-PUMP-RADIATOR-2ND GPU-1ST GPU- RES is it fine?

i agree, but MCW80 and using RAMsinks is not good fore SLI, IT WILL BE NOT SO EASY TO BEND 1/2 . am i right? and i will wait for 580 card, and I also read that NVDIA will release new cards after new year.

and also i want to know is quad rad. will be good to cool 2 GTX 480 or i need some thin extra?

I run SLI GTX260's with MCW60 blocks and RAMsinks. It would be almost the exact same setup as I described for you, just different block models (the MCW80 is the newer version). Where do you get your info?

Yes. It is very possible to bend if you get tubing with good flex properties, such as Tygon or Feser...there are others as well.

but for RAMsinks i would need a good air flow in the case or it is not necessary? price is not a problem, i think that full block is still better.

If price is no issue, then sure, go that route. If you have a case with good airflow, you would be fine in most instances with RAMsinks. Your call, just providing as many options as possible for you to make an educated decision for yourself.

thank you for your help. quad RAD will be enough to cool 2 gtx 480 ??

i will run separate loop one is for CPU triple rad and one fore 2 gtx 480 quad rad

Yeah, you should be fine.

Best answer selected by matvey.