AMD's trinity (any APU) is a aimed at very low budget and entry gaming. They have 2 lines of processors, the APU and "enthusiasts" as I like to call it. You will want to upgrade to a better CPU such as the 6300 or 8320/8350, along with a new CPU you will also need a compatible motherboard. The motherboard you have right now is an FM2 motherboard, FM2 is made specifically for APUs. AM3+ is for their enthusiasts.
To sum up, yes your processor is very weak, aimed for entry gamers. You should upgrade to a better CPU. Since you are considering the GTX 670 I would assume you have a lot of money at hand. I highly recommend upgrading to a new processor from AMD or Intel. Something like the 6300/8320/8350 from AMD or the 3570K from Intel.
If considering an upgrade from AMD's path I recommend a 8350 and a Gigabyte 990FXA-UD3. If considering Intel I would get the i5 3570K along with an ASrock Z77 Extreme4.
Your power supply is also a bit overkill. Remember a PSU is only MOST EFFICIENT at around the 40% to 50% load mark.
Best to save up a little more and get a better processor from Intel which may be more expensive but its better. For 2 7870s you should get something along the line of i5 3570K. Remember a Intel chipset refresh is impending might be worth a wait should push down this gens prices down and you might get lucky and see the 700 series from Nvidia.
Take it easy there buddy. First and foremost I would HIGHLY recommend that you upgrade your CPU first. By doing this, in the future you won't be like "why is my GPU performing so bad compared to this person's". If you still want to game, I would suggest you get a 7770 to 7870 series of graphics cards. When you have saved up enough, grab a 3570K or an 8350.