About 3 months ago my motherboard died and I have since been given a replacement (of which could have been a refurb or new, I don't know). Once everything was up and running again the computer started to completely freeze at random and the only thing I can do is power of and on again. There's no indication when it'll happen. I can just be browsing or playing a game and the screen will freeze, sound will stop playing and the HDD light will either be stuck on or off, a complete system lock up.
My immediate response was that they had sent me a crappy refurbished board that hadn't been fixed properly but there's no proof to suggest that it is. However sometimes the graphics card will play up and start displaying artifacts on the screen on some occasions, usually after it has locked up 2 or 3 times. It'll either be horizontal lines over the screen of colour corruption (lots of pink and green pixels scattered). I've taken a picture below showing an example (excuse the quality) on a white background.
Before the motherboard died this never happened once so I can only assume the GFX card was damaged. It has always been a bit dodgy as I have to under clock it just to stop corruption in games. The 1 year warrenty was already up by then so no RMA but it was OK for like 1 or so years and the underclock didn't reduce FPS by any noticeable amount in the games I played.
Because this system crashing never occurred before I can't rule out that the motherboard or any other component for that matter is responsible. I also don't have a spare PCI-E card lying around to use or a spare motherboard to test with.
I thought I could just live with the problem as sometimes it can go without crashing for many days but then suddenly it'll freeze up 10 times in a row before finally becoming stable enough to use for any length of time. It usually does it on a cold boot but it has also done it after being on for many hours. Strangely it'll more than likely crash while web browsing or just after start up than it will when playing an intensive game (it's only done it about 3 times).
The card is a Powercolor 4870. It's pretty old so I may as well replace it even though it's enough for my needs ATM. The only problem is that I don't know for certain that it is the fault. The corruption could be caused by the numerous powering off and on again when it freezes up. Usually after a restart it'll go away. It's currenly using the latest ATI Catalyst and is also still underclocked with ATI Overdrive (500MHz / 450MHz).
My immediate response was that they had sent me a crappy refurbished board that hadn't been fixed properly but there's no proof to suggest that it is. However sometimes the graphics card will play up and start displaying artifacts on the screen on some occasions, usually after it has locked up 2 or 3 times. It'll either be horizontal lines over the screen of colour corruption (lots of pink and green pixels scattered). I've taken a picture below showing an example (excuse the quality) on a white background.

Before the motherboard died this never happened once so I can only assume the GFX card was damaged. It has always been a bit dodgy as I have to under clock it just to stop corruption in games. The 1 year warrenty was already up by then so no RMA but it was OK for like 1 or so years and the underclock didn't reduce FPS by any noticeable amount in the games I played.
Because this system crashing never occurred before I can't rule out that the motherboard or any other component for that matter is responsible. I also don't have a spare PCI-E card lying around to use or a spare motherboard to test with.
I thought I could just live with the problem as sometimes it can go without crashing for many days but then suddenly it'll freeze up 10 times in a row before finally becoming stable enough to use for any length of time. It usually does it on a cold boot but it has also done it after being on for many hours. Strangely it'll more than likely crash while web browsing or just after start up than it will when playing an intensive game (it's only done it about 3 times).
The card is a Powercolor 4870. It's pretty old so I may as well replace it even though it's enough for my needs ATM. The only problem is that I don't know for certain that it is the fault. The corruption could be caused by the numerous powering off and on again when it freezes up. Usually after a restart it'll go away. It's currenly using the latest ATI Catalyst and is also still underclocked with ATI Overdrive (500MHz / 450MHz).