Okay, so to start off from the beginning, my PC had been giving off a strong whirring sound for quite some time. I didn't really pay attention to it. But after a while my graphics card crashed from overheating because as it turns out, my GPU's fan wasn't functioning properly. After the crash my PC wouldn't boot. But then it did, my monitor was giving off these strange red lines and artifacts. So, what's really bothering me is the fact that these artifacts would sometime go away and my PC would return to normal on restart. Later that day everything was working fine and I thought the malfunction was just the aftermath of overheating. The next day, the artifacts returned and wouldn't go away for two days, so I figured my graphics card is probably dead and started searching for a new one. Yesterday though, I was listening to some music and I left my PC on standby to go and do something, and when I returned the artifacts and red lines were gone. I was happy because I knew my card isn't dead. But naturally today, it isn't working anymore 
So I'm wondering what could be the problem, I've reseated the card and RAM, I've looked up every possible thread and case on the internet for solutions. I have the latest driver for my card, which is an Nvidia GeForce 9800 GT. My fan is properly oiled now and is working properly, my PC gives off virtually no sound. If you need any PC specs inform me but I don't think they are relevant.
So to sum it all up, my graphics card is blocked by windows (error 43), but occasionally it works fine. I would like to know what the problem might be and how I can fix it.
Thanks.

So I'm wondering what could be the problem, I've reseated the card and RAM, I've looked up every possible thread and case on the internet for solutions. I have the latest driver for my card, which is an Nvidia GeForce 9800 GT. My fan is properly oiled now and is working properly, my PC gives off virtually no sound. If you need any PC specs inform me but I don't think they are relevant.
So to sum it all up, my graphics card is blocked by windows (error 43), but occasionally it works fine. I would like to know what the problem might be and how I can fix it.
Thanks.