I recently purchased a new system but it has been struggling to run practically every game I try. I have up to date graphics drivers.
Looking for some advice on what to upgrade and why I get such low performance on many games, such as Borderlands 2, I get 20 frames even on the lowest settings.
AMD FX-4100 CPU - 3.6GHz
4G DDR3-1600MHz RAM
500GB Hard Disk
ATI HD5450 Graphics Card
Suggest you look for published frame rates for the fx-4100 and hd5450 and see if you are worse or roughly the same. I suspect that you are already getting all you can from the home theater (not gaming) video card and the not-real-good for gaming CPU.
Look at the last pages of these two articles to see ratings of CPU and video cards. Find your cpu and gpu and see what's stronger. Video cards are very easy to replace and will have the most gaming impact. CPUs are harder, especially if you needed a MB swap.
But as suggested the radeon 5450 is not a gaming card . Its more for playing DVD's
You dont say what kind of power supply you have , but if its a decent 450+ watt unit you should be able to drop in a Radeon 7850 for about $170 and then game very well