First things first.
Which resolution do you intend on playing at? If it's just FHD, or 1920 x 1080 you'll be in the clear.
Do note however, that the motherboard you choose doesn't support resolutions higher than FHD, in the event you want to try.
Another thing is that the chipset, H81, isn't the most ideal for gaming. Z97 or its like, would be more suitable.
If you want to save some money, downgrade your HDD to a Caviar Blue. It's still good. Just avoid Green at all costs.
We also don't know your budget by the way.
If you asked what an SSD is needed for, I can explain. An SSD is a flash based storage medium.
Unlike the HDD, the Caviar Black, which is based on spinning magnetic disks.
SSDs are faster, less prone to failure if you drop them, quite reliable and silent. However
they are still very expensive. 128GB is the sweetspot for SSDs on cheaper builds. Otherwise 512GB is usually the next step.
If you store Windows or other files on the SSD, they will load much faster than on an HDD. As for the CPU, if you're the tinkerer
type, I recommend that you get a CPU with a K attached. This means it can be overclocked, which means you can net more performance.
I also recommend that you step away from pcspecialist, as the options are quite limited there. Instead, check out
http://uk.pcpartpicker.com/
Another question. Will you be using this build for any sort of editing work, such as video or image editing?
There's also the issue of which resolution you will run at and whether you need peripheral items or not.
Here's an example build, which is vastly better than yours in many ways.
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i5-4690K 3.5GHz Quad-Core Processor (£174.90 @ Amazon UK)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£26.34 @ Aria PC)
Motherboard: Asus Z87-A ATX LGA1150 Motherboard (£114.30 @ Ebuyer)
Memory: G.Skill Ripjaws X Series 16GB (2 x 8GB) DDR3-1600 Memory (£98.42 @ CCL Computers)
Storage: Samsung 840 Series 120GB 2.5" Solid State Drive (£82.04 @ CCL Computers)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (£42.95 @ CCL Computers)
Video Card: EVGA GeForce GTX 980 4GB Superclocked ACX 2.0 Video Card (£463.28 @ Ebuyer)
Case: Corsair 200R ATX Mid Tower Case (£46.39 @ Aria PC)
Power Supply: Corsair Builder 750W 80+ Bronze Certified ATX Power Supply (£64.99 @ Amazon UK)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer (£11.95 @ Amazon UK)
Operating System: Microsoft Windows 8 (OEM) (64-bit)
Monitor: Asus VG248QE 144Hz 24.0" Monitor (£239.00 @ Amazon UK)
Total: £1364.56
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-04-19 22:27 BST+0100
So if you do have a lot of money, then this can be yours. I included a screen just in case you don't know which one to pick.
It's well suited for fast paced games due to the low response time. It's an excellent screen. The only major drawback is
that it doesn't have IPS. IPS, or in-plane-switching, makes things more beautiful and vibrant looking. Also improves viewing angles.
This build is great because it has options open. You get one of the latest GPUs, with a lot of VRAM at 4GB.
This makes it ideal for loading lots of texures, as in ARMA. Or if you use lots of mods, like in Skyrim.
The CPU is also newer, overclockable and faster. The motherboard is also better suited. You also get more
RAM. You won't have to go beyond 16GB for a long long time either. So in short, it's top notch. If you want it
cheaper, I can make it cheaper for you.
Of course this would all require that you put together the parts yourself or find someone to do it. But that's also the best way too.
Hope this helps.