Upgrading PCs, can't decide on CPU or graphics card

[Samantha]

Hi, I am trying to upgrade two computers, one has a athlon ii x2 250, 4 gb memory and a msi hd 6670 graphics card, and the other pc is a athlon ii x4 650, 4gb memory and msi hd 6670 graphics card,
I am trying to decide what to get, I can either only get a cpu/motherboard/memory or a single graphic card im not able to get both.
I was considering the hd 7850 for graphics card
or I was thinking of getting the a10 5800k, and doing dual graphics.
I know either way im getting an improvement for both pc's but I cant decide which one would be a better improvement. I also heard that getting a good graphics card with a crappy cpu itll throttle the gpu,

 

[cliffordcooley]

What is you current setup?
What is your budget?

Can you upgrade the CPU to at least x4 or possibly an AM3+ CPU without purchasing a new motherboard?

Edit:
It is worth mentioning that if you are using an OEM Windows version, purchasing a new motherboard will invalidate your Windows license and require a new license. So changing motherboards for people who have an OEM install has additional cost, which many people don't know or think about when making decisions.

 

[Samantha]

Have to upgrade motherboards, currently running am2+ socket motherboards
current budget is around 500 dollars, and need to upgrade both pc's

I could upgrade the one dual core to a quad core np, but if I get a cpu iw as planing on a new motherboard and the new ram, cause im upgrading to ddr3 8gb of memory.

 

[cliffordcooley]

So something like this is what you had in mind?

GIGABYTE GA-F2A75M-D3H FM2 AMD A75 (Hudson D3 -- $90
AMD A10-5800K Trinity 3.8GHz (4.2GHz Turbo) Socket FM2 -- $130
Kingston HyperX Blu 8GB (2 x 4GB -- $37
For a total of $260 for each PC.

or with comparable CPU performance on AM3+ platform

GIGABYTE GA-970A-DS3 AM3+ AMD 970 -- $80
AMD FX-8120 Zambezi 3.1GHz Socket AM3+ -- $160
Kingston HyperX Blu 8GB (2 x 4GB -- $37
For a total of $280 for each PC.

 

[Samantha]

So tis still up in the air what would be a better upgrade an a10 5800/motherboard/the 8gb of ram, or just a gpu a 7850

 

[Ritwik7]

That would mostly depend on what you will be doing with your PC. If they're to be for gaming, then you'll be better off buying a couple of HD 7870s for the $500.

In case you're running multi-threaded, CPU intensive applications for audio/video/image editing or designing, etc., the CPU upgrade path would make sense.