the graphics card runs around 47c to 55c
I am guessing that is an idle reading. This is perfectly OK. I have seen reviews of 5750 cards where the 100% load temp with stock cooler went over 80. 65 to 75 being typical. A query on an AMD gaming forum "What max temp is OK for a 5750?" produced the answer "Anything below 100C is fine." and "Under full load I've never seen a 57XX series above 85C" Another thread contained "My HIS 5750 IV Cooler hits 65C at Full Load 35C Idle".
So you can see that you might see a temperature difference of 30 degrees C or so between idle and sustained full load. Some HD 4870 cards show around 90 on full load.
The bottom line is when does the silicon start to malfunction, and when does it suffer irreversible damage. I have read that the statistical lifetime profile for commercial modern-process silicon is roughly halved for every 10 degrees C above 75 degrees C. "core" temperature. What does this mean? In "Gerontology Of Silicon Integrated Circuits" (2000, M I Gorlov and A V Strogonov, Russian MicroelectronicsVolume 30, Number 2), the "rated lifetime" of "domestic" (i.e. non-military/high spec) ICs is given as 200 x 10^3 hours (25 years is a good enough approximation).
One reason why GPUs can run hotter than CPUs is that (I think) the geographical workload in a GPU is probably fairly evenly distributed across the chip. If the chip is at 100°, then the hottest on-chip temp is also probably near 100°. On a CPU, the hardest-working parts of the chip occupy a substantially smaller fraction of the total chip area. I don't think it unreasonable that a CPU with a chip temperature of 60° above ambient while dumping 100W could conceivably have spot temperatures that are 10°, 20°, or more above that.
Products like graphic cards are designed for world wide use, from icy Alaska in winter to sweltering India in summer. Many NVIDIA products are rated up to 120C. ATI stuff is said to be OK at "anything under 105". Many people in India are used to idle temps around 60 and full loads over 85. These readings would send many people in the temperate zones running for fancy coolers. Especially teenage gadget heads with money to spend on "number chasing". Many third party hardware companies thrive on this phenomenon.
Which brings me to the point. From what you have written, and from a bit of Googling I have done, your card is working perfectly well, is absolutely within its design limits, and does not actually "need" water cooling. If you want to go ahead and fit water cooling, then be aware that you are doing this just because you fancy having a cool* pump and pipes and block etc to gloat over and show your friends and provide a "pride of ownership" feeling. I will not comment on this beyond saying many of have been there too. There is a problem, however, and that is as follows: due to its physical design, your card cannot take a full water cooling kit, (you were told this in another thread) and...
There isn't full cover waterblocks for the 5750, you must get universal GPU blocks but those only cool the GPU and nothing else.
So you would only get a partial solution anyway. It would be like putting a bride's dress on a pig. It wouldn't make her any more sexy.
Pardon me for saying this, but you have displayed an amazingly cast-iron determination to ignore well meant, well researched and well checked advice, and I am feeling very puzzled why you have chosen to go to a general forum like Computer Hope with your query, when five minutes of Googling would have found you a ton of more specialized forums where gamers, overclockers, and modders all share their knowledge and experience, and where (I suspect) the answers you get might be much less polite than the ones you got here that you didn't like.
*No pun intended.
