Hi monsterhunt, welcome to TSF
Please post a screenshot of the multi-coloured lines. It sounds like overheated VRAM on the graphics card, either caused by the inside of the case not being properly ventilated, or a problem with the PSU.
Are you using the latest graphics driver, chipset drivers and DirectX?
Are all the case fans free of dust and spinning? (especially the graphics card fan)
Try and leave a fullscreen game running for as long as possible and get some readings for temperatures and PSU voltages during gameplay using PC Wizard.
Please post a screenshot of the multi-coloured lines. It sounds like overheated VRAM on the graphics card, either caused by the inside of the case not being properly ventilated, or a problem with the PSU.
Are you using the latest graphics driver, chipset drivers and DirectX?
Are all the case fans free of dust and spinning? (especially the graphics card fan)
Try and leave a fullscreen game running for as long as possible and get some readings for temperatures and PSU voltages during gameplay using PC Wizard.