OK, sounds like you need almost exactly what I built. I do much the same, some fairly high end PC games as well, but I'm not what I would call an expert gamer. I do play allot of RPG's, action games and FPS games so I wanted a decent vid card for sure. I went pretty much mid-high video card, with a nice modern 8 core CPU setup and build around that.
I'm a stickler for performance and bang for your buck. ALL of the products I listed below consistently review 4.5 or 5 out of 5 stars on various credible tech sites or through public reviews on amazon. I research for days

I usually go Intel/nVidia for my builds, but over the last 10 years AMD made huge leaps and bounds and bought out ATI and now their stuff is really nice.
Here is what I purchased (but remember I used to work in a tech shop and built my own);
This Motherboard is top of it's class, it's typically a high end gaming board, comes with a billion options (can have up to 32 gigs of RAM)
ASUS M5A99X Evo R2.0 ATX AM3+ DDR3 AMD 990X 3PCI-E16 2PCI-E1 1PCI USB3.0 SATA3 GBLAN Motherboard $153.47
The Brain. If your PC is older then 5 years, then your CPU is crap. I can't believe how fast the CPU's are now. This CPU is 8 cores (that's 8 CPU's in one). Dominates for multitasking. You can quite litterally play a game, install programs, have Photoshop open, mail open all at the same time with little performance loss.
AMD FX-8320 8 Core 3.5/4.0GHZ Processor AM3+ 16MB Cache 125W Retail Box $173.90
My Vid Card, I fairly high end card that can play most modern games are medium or high graphics default. I got this card specifically because it's super quite and requires little power for what it offers in return. This card is also over-clockable right out of the box with software. Stays very cool thank to aluminium heat sink and copper pipes, dual fans etc.
Gigabyte Radeon HD R7 260X 1188MHZ 2GB 6.5GHZ GDDR5 2XDVI HDMI DisplayPort PCI-E Video Card $152.33
Hard Drive... typical nowadays. Yet note the size, 2 Terabytes!!! yahoo!
Seagate SV35 Series 2TB SATA3 7200RPM 64MB Cache Surveillance Hard Drive $104.63
Not the best RAM on the market, but pretty dam close. Definitely the best brand for reliability and speed. A spent allot more here then I had too, but I wanted RAM I would never have to replace for the next 10 years.
16GB KIT 2X8GB 1600MHZ DDR3 DIMM XMP CL10 HYPERX BLACK SERIES $220.80
Total with tax: $915.27 (we have 12% sales tax here in BC)
Ontop of this you will need;
A Case with a good modern powersupply (430 watt or better)
If you can find someone to build that for you or find a place to buy a comparable PC to these specs you'll have a very nice computer for many years to come
