Upgrading my PC - buy a new card or not?

[Addicus2888]

Im building a new PC on a tight budget. A while back I upgraded my old one by just getting a better GPU - ATI Radeon 4870 512mb.

I am going to build a new machine now for about $600-$700. My plan was to just steal my 4870 for the new machine and stick something slightly worse in it for resale purposes. That would work because currently the 4870 is too powerful for my current PC. After looking at the prices of some of the GPUs out there, though, I was wondering if it would be worth it to just upgrade completely and leave the 4870 in my old machine.

So my two options are:

1. steal my Radeon 4870 512mb for my new PC and spend about $35 on another Radeon for resale purposes.

2. Buy something like the Radeon 5670 1gb for $80.

On a tight budget is the new GPU worth $45? How much better is 1gb GPU memory versus 512mb? How much better is the Radeon 5670 than the 4870? Would it be worth it to spend even more money on something better than the 5670?

I would include the specs of the new PC that I am building but I havent put it together yet. All I know is it will cost around $600.

Thank you for the input.

 

[mactronix]

Ok first things first a bigger number dosent automatically mean a faster GPU. the 4870 has about 60% more performance than a 5670.

Mactronix

 

[Addicus2888]

Ah, so it would actually be a downgrade except for the difference in memory? Whats different about the series then?

 

[mactronix]

Well how long do you have ?
Basically its roughly the same as far as the internals go no new Archetecture worth talking about. DX11 is suported on a 5 series card DX10 on a 4 series card. Some changes in power usage also.
Probably best for you to read a review of both and then come back with any questions.
http://www.techpowerup.com/reviews/Diamond/HD_4870/
http://www.techpowerup.com/reviews/Axle/Radeon_HD_5670/27.html

Mactronix