8600GT by Gigabyte: composite signal too low?

Hello, I am new to this forum but I really need your help. I tried to connect my TV (really cheap Samsung with single RCA for audio input and single RCA for video input) to my PC's video card and have failed. My card is Gigabyte GV-NX86T256H with dual DVI and single TVout which in fact requires the additional connector with 3 RCA and 1 S-Video female slots. So I inserted that connector into card's TVout and inserted the composite (RCA-RCA) cable into the slot marked with Pb/AV. I got some picture of my windoze desktop on my TV, but it was very unstable and noisy. I suppose that it is because I used too long cable, 5 meters, and the card's output power is not enough to keep the signal high at the end of cable. But I can be wrong. Can anyone tell me what the problem could be? Maybe there is some software solution to make the video card produce stronger signal?

I have too used a composite cable but the quality coming from my 9800 pro was horrible anyways. I honestly could not look at the TV for more t han 5 minutes but it was still cool for the 5 minutes I had it setup. I don't believe it's your card but the general connection itself. Sometime if I wiggled the connection the strobing effect I had would fade or grow, fuzz would come and go, in general it should be avoided.