What's the difference between a hd7870 and a hd7870 ghz edition

ghz should be faster and cost more. So if you can get them at the same price, go with the ghz instead. But if not, Consider getting the plain 7870, then OCing it can match the ghz.

Look into the 7870 LE while your at it.

If you show us your build you plan to get, its possible you can get a 7950 (assuming you save money in the right areas).

There's no non-GHz edition. All HD7870 (non-LE) are GHz edition (meaning they are clocked at 1GHz or more on the core).

There is however an HD7870 LE/HD7870 XT. Instead of using Pitcairn GPU, this card is based on Tahiti (used on 7900 cards) but features slightly lower clock speeds than the normal HD7870. However, it is slightly faster than the standard 7870 (also slightly more expensive) and clock speed varies depending on the manufacturer (they'll probably come factory overclocked as well).

GHz edition or not, it really doesn't matter to be honest.

The System is as follows:

Case - CM Storm stryker
Mobo - Asus P8Z77 - vpro
CPU - i5 3570K
Memory - Corsair vengence 2x4 Gb 1866
PSU - Corsair HX 750
GPU - ?????? saphire hd 7870
HDD - 1 TB WD Black

Thing is I want a solid system that performs and still gets good bang for the buck. ie I don't need it to be the cheapest hence the good PSU, case and mobo but I want it to last and not totaly break the bank.

I would tweak your build to make the most out of your budget,
I'm guessing that you'll overclock and go dual video card in the future...

1. Change your mobo to other z77 board, v-pro or other z77 v's fo asus is just way too expensive and you'll have the same features as other boards, I would never suggest a v board unless they are on sale or really cheap. I'll probably suggest you get a asrock z77 extreme 4.
2. Change your ram to 1600. You don't need a 1866. 1600 will be fine for you.
3. With the saving you had, you can up your build to hd7950. You can stay with sapphire.
4. Also, don't forget to add a cpu cooler once you plan to overclock. a hyper 212 evo will do for you.
5. You psu is great and enough for dual video cards.
6. If you plan to add an ssd in the future you might as well change that hdd to blue to save you money but if not, then you can stay with black.

I think your right about saving some money on the mobo though I will say that the extreme 4 is no where near as feature rich as the v-pro hence the near $100 price differential. I'm thinking that the extreme 6 may be a good compromise. toms recomends it in the enthusiast bracket. Either that or how do you feel about the MSI boards in the same price range? as far as the ram goes the price difference at direct canada was like $5 so I figured why not go faster? Thanks for the suggestion about the HDD I am planning on an ssd in the near future and the blue will definitly save me a few bucks ..... whats the difference between blue, black , red, green? Thanks for the suggestions I do have a CPU cooler lying around ...... a CM v8 ......... not ideal but free.