ok i have made my last desicions, but i am not fully sure if they would work together. I have a AMD A6 3620 APU... it is probably quite laughble but it gets the job done for a newbie like me but i would like a bit more out of it so i was wondering if it would work/crossfire with these and which would be better.
Yes, the A6 will work in asymmetric crossfire with a HD 6570, but it won't work great with everything. Here is one review if you are interested: http://www.anandtech.com/show/4476/amd-a83850-review/6
There isn't really a point in getting a 6570 with 2gb of memory, especially for that price. Something like this would be a much better deal: http://www.newegg.ca/Product/Product.aspx?Item=N82E16814150613 basically the same thing but for $49.
If you're willing to spend that much money just get something like this: http://www.newegg.ca/Product/Product.aspx?Item=N82E16814202021 and forget about the asymmetric crossfire. This will give you better performance.
Yes, that's correct the 7750 will give you better performance. The problem is the crossfiring with your apu has poor scaling, so it is not like you get the sum of the performance of both gpus.
The 7770 is a lot of GPU for the money, and it should be just about right so that your processor doesn't bottleneck it. You can find the MSI OC version (not the GHz one) for a good deal and it has much better cooling and potential for overclocking.
i'm gonna recommend this. for a 7750 you'll want the 1gb DDR5 over a 2gb DDR3. You will almost never make use of the extra GB of space, but the memory speed increase from DDR5 over the DDR3 will be more noticeable.