LOL, I've noticed that before and thought maybe guru3d had been hacked. Dunno what it is for sure though...
It's been like that for a long time! I noticed it when I first joined..xD. Just hover over the banner. Btw, it's alt codes, like: <img src="image link here" alt="random text here">
It's not on the homepage, set your forum theme to ambience (yes, it's misspelled), and look at the header.