That's not the PC that says 'power saving mode', that's the monitor telling you it gets no signal.
A common reason for that is an issue with the video card. If you find it easier to try another monitor than to try another video card, just do that. You never know if it helps. If it doesn't replacing the video card is the second thing to do. Your post doesn't tell if that's something you can do yourself.
Hello guys ! I'm searching for some advice ! Note: I don't really know much stuff about computers.
I've used my PC for 5 years and everything was fine. This summer I left it for a couple of months and when I started to use it again it went crazy ! Sometimes when I turn it on, the display stays dark with "power saving mode". Sometimes the display turns dark and everything stops in the middle of the work for no apparent reason. Sometimes it goes pink. And one time it went blue. Sometimes it's just my computer that stops responding. I've tried so far: cleaning the dust inside - it's already squeaky clean ! I reinstalled winXP (afterwards the problem persists, but not that often like before) ! I updated NVIDIA GeForce drivers ! What else can I do myself to solve this problem myself ? Thanks !