Having recently found out and tried bitcoin mining I am looking at upgrading my GPU, currently I have a Nvidia GTX 460 1GB, not great for mining but plays my games great.
Everything I have read says the 5xxx ATI cards are best for mining so looking around I found the following: (http://www.aria.co.uk/Products/Components/Graphics+Cards/ATI/ATI+5800+Series/Gigabyte+ATI+Radeon+HD+5870+Super+Overclock+1GB+GDDR5+PCI-Express+Graphics+Card+?productId=44876
This comes overclocked at 950mhz on the core out of the box with the ram clocked at 5Ghz, given that this costs £150 which is the same I paid for my 460 not so long ago I was expecting about 6 - 8 times the mining performance. This seams like really good performance for the money far to good almost hence why I wanted to double check before buying (hell someone I know will by my nvidia for £120 so I will only be out by £30).
The other question I wanted to ask is on overclocking what gives the best performance for mining core clock or memory clock? these cards are supposed to have plenty of extra headroom for higher overclocking so I will want to get the most out of it.