Routers are static firewalls. They have great firewalls, but with a few drawbacks as well. They can be used, but I still recommend you get a dynamic (software based) firewall because the code for the dynamic firewall changes while a Routers firewall changes you IP, which can be hacked and then spiked to continually send the virus each time it detects you don't have it again (aka after a reformat). keep using the firewall, but if there is a way (I don't know if there is or not) have the Router change its IP as well if at all possible.
BTW- I dont screw with routers all that much, just lets ours do its job, and have firewallls on each PC as well.
BTW- I am right about PS and GPU, just that is very rare, and Like I said, that usually happens when you upgrade components (especially GPU) and PC doesn't have enough power to run properly. Call up a graphics card designer and tell them your PC shuts down after about 2-5 mins of operation and that you just installed one of their graphics cards, and they will say the samething. I am not calling you a dick, just don't think I am BSing these answers pls. I am on this forum to help, which is why I said it COULD be one of THREE problems, and then I said that it was MOST LIKELY as VIRUS... So, my other 2 solutions are probably not correct.