Or higher numbers on the product name don't always equal higher performance.
https://en.wikipedia.org/wiki/List_of_AMD_graphics_processing_unitsI have $100-ish to spend on a GPU for mining scrypt coins, and also plan to do SHA256 along with a couple of block erupter sapphires (I got them really cheap) and will likely buy an Antminer U2 or two since they're faster and cheaper than the U1.
But right now I need a GPU that's not stupid expensive and won't be a gigantic waste of money due to it having a model name that makes it seem like it should be fast when it's likely one from the previous generation that was higher up the performance ladder will outperform it.
My electricity cost is 6 cents a kilowatt hour.
I bought a Sapphire Radeon HD 6870 with 1GB DDR5 in an auction lot, supposedly new but it damaged two motherboards. One was my olde Socket 939 board, the other was a $40 OEM Asrock 770 Extreme3. I figured that perhaps it killed the PCIe bus on the 939 from pulling too much power for a 1.0 spot, even though I had both 6 pin plugs connected to the board. I first tested the Asrock with an 8800GT, booted fine. Then I plugged in the 6870 and @#%@#%#%^%@#@%@!!!!!! Deader than the 939 board, which stops POST at 6b (if I had an old PCI video card it might still work). The Asrock just goes straight to FF.
(I'm getting a replacement board, same model.)
If the card could be repaired cheaply... but Sapphire won't touch it, not even for $.
If your Sapphire dies out of warranty, you're screwed.
The best GPU I have now is a nVidia 9800 GT 1GB. It averages 20-ish Khash on scrypt and can peak at several Mhash (I forget just how high, IIRC I saw around 100 with the latest BFGminer) on SHA256 but it won't maintain that top speed for some reason, varies up and down a lot.
I've been working with computers for over 30 years and have always been a bit of a cheapskate when it comes to buying hardware. I wait for prices to drop to what I consider non-insane instead of being an early adopter throwing money at the latest shiny object.
I remember when hard drives first dropped to $1 a
megabyte. 500 megs for $500! Then I was able to buy somewhat smaller drives for peanuts, and laugh at those who bought the 500's when the 750~800's came out for less than $1/meg.