I shut down my computer a couple days ago and when I restarted, it got to the desktop (Windows Vista) but suddenly the monitor went to its standby mode. Now sometimes I'll reset it only to have it happen right away. Last night I had the computer running OK until a little bit ago when we went out, and it happened again.
I've noticed that when this happens, the CPU itself is really making a roaring sound like it's working hard. If there was any audio coming through on the speakers or headphones, it'll get stuck looping until I shut the system down. I bought the PC about two and a half years ago. I'm wondering if maybe the power supply needs replacing but I'm not too experienced with PC hardware. I opened it up yesterday and dusted it out pretty well. It's a Gateway DX4300-03:
AMD Phenom X4 9750 Quad-core
ATI Radeon HD 4650 1024MB
8 GB DDR2
More about :monitor sleep mode cpu stops working properly
I'm actually making this post from another computer as I've been unable to get my own working now. It will not have anything show up on the monitor at all and I just end up needing to shut off the CPU.
I ran a game and I noticed that the very first temperature reading went up just from the main menu of the game. It was about 56C or so when I alt-tabbed out to check and had the flame symbol. I tried to start a game on there and it went through the loading process and played the level a bit before it stopped working. I shut it down and unplugged it for the night and tried again in the morning but couldn't get it up and running.
I tried doing the new power supply on the computer put no change there.
I was also able to do the battery on the motherboard and not really much there either. Just for the sake of trying, I took the monitor plug out of the graphics card and put it into the other monitor port on the computer. There was a kind of bootup screen and I selected to load the previous settings (looks like maybe I shouldn't have chosen that option). There was a Windows loading screen for a bit then came up the blue screen of death. I did see something on there referring to ataport.sys which leads me to believe I didn't connect something right when I put it back together, but I can't imagine what that might be.
Bit of an update: I tried plugging in my computer yesterday and it started running like normal. It got to the desktop but it only showed my wallpaper, no pointer or start bar or anything. I unplugged one of the cables from the monitor to the computer and that set it back to normal. I left it like that and was able to move some important files to a flash drive and then experiment with it a bit. I tried running a very mild game (Dwarf Fortress which is not graphics intensive at all) and that ran fine. A while after that, I started up the Sims 2 but the resolution was off. I had it in one of my neighborhoods and was trying out the different resolutions when it stopped working. However, the music in the background was still playing fine until I tried doing alt-tab out of it then go back to it and it was still playing normally.
So, at this point, I'm starting to wonder if it might actually be my graphics card going bad. I'm going to download updated drivers from this computer and do what I can to install them on my own. However, if this doesn't work, I may end up buying a new graphics card. Do you think a bad graphics card may be the problem?
I actually did the drivers update and so far it's been running fine. Had it on for about a full day now. It's actually running better than before the issue was happening. Hardly makes much noise anymore. Just for the sake of checking, I ran SpeedFan earlier and I saw that everything was OK, just the GPU was up around 59-60C (while running a game). Would this be an issue or is it fairly normal?