Bsod, over and over again

Hello, I only use my pc for Playing Minecraft/runescape, or browse the web, but I constantly get random Bsod's and im really really sick of it, im desperate for help, I took my pc for repair, they wiped everything (as I asked) and installed Win8, I thought that'd fix it, but no. First day of Win8 usage, Random Bsods. already cleaned and checked with memtest etc. Please Help me :(
Another issue. I cant post Minidumps, I click the Upload a File button, win8 takes me to this weird archive explorer, I already made a folder with the minidumps under documents folder, but when I click it, they arent there! D:
 
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