If you are having a lot of noise from your GPU, it is likely because you aren't getting good enough airflow to the current cooler to allow it to run at a slower speed. Even if you got a LCS cooler for your GPU, it would still likely be loud for 2 reasons:
1. Most LCS coolers use/need high CFM fans to cool their radiators due to the dense fin design. Most need push/pull fans to accomplish this.
2. If you don't have good case airflow, even watercooling will under-perform. Every cooler, regardless of design, needs good airflow.
What temps are you seeing at load? I'm guessing if your GPU fan is loud, you might be seeing some decent temps at load.
You can also pull your stock cooler and replace the TIM with some better thermal paste. This often gets you 5-8C better temps at load (considering you have good case airflow).
Sounds like you have a case airflow problem. To test, do the following:
Remove the side of your case, blow a house or desk fan (on high) into your case.
Benchmark, game, encode video...etc. Get your PC to sustained load temps.
If you see lower temps with this method, you have a case airflow problem...a better cooler likely isn't going to help a great deal since you already have poor airflow. If your temps stay the same, you have a hardware cooling issue and should then look at better cooling options. Remember, buying a great cooler isn't going to help if your real problem lies with your case airflow to begin with.
Can you post some pics of your case (door on and off) as well as some system specs and ambient temps?
I have a VF3000a on my 5870, and the thing is awesome. I know it's not water cooling, but with this thing you don't need it. While playing BC2 1680x1050 all on high 8x anti aliasing keeps the card well under 60c and the vrm's under 70c, that's in an 85F room. Under normal conditions say 70F, it never goes above 45c and 60c vrm. It's also pretty quiet compared to stock coolers, just make sure you have half way decent air flow.
BTW those numbers are 960 core and 1240 memory. Gonna go for 1000ish maybe 1050 when I get bored or Battlefield 3, what ever comes first.