HD Radeon 7870 and my PSU

[kearon]

I recently built my first computer and was quite happy with the results, but I am itching to upgrade =) I am looking at getting a Radeon HD 7850 or Radeon HD 7870, each seem to be great cards and fairly future proofed (stop me if I'm wrong).
I noticed on newegg that all of these graphic cards said that they need a minimum of 500w PSU so here is my question, I have a 500w but do i need to upgrade?
The GPU I am looking at is: http://www.newegg.com/Product/Product.aspx?Item=N82E16814125418 (it had the best ratings on Newegg and I don't really know manufacturing names yet)

The PSU I have is:http://www.newegg.com/Product/Product.aspx?Item=N82E16817139027

And I would appreciate it if you could point out the technical reasoning behind any answers, still new to the whole building a computer thing and appreciate any teaching so I can understand stuff more in the future.
Thanks!

 

[swilczak]

The Radeon 7850 and 7870 are more power friendly than the last generation 6850 and 6870 GPU's. Newegg has a power supply calculator, if you click on the computer hardware tab on the main page you will see it. Enter all of the details of your system and it will give you a rough estimate of what you need. You didn't give enough details about your system for me to say you have enough power, but it sounds like you do since your power supply is 80 plus bronze certified and a good reliable brand. Always remember that the more head room you have in your PSU, the more cool and efficient it will be.

 

[kearon]

I punched the info into Newegg's PSU calculator and it said I would need 490w (so 10w less the my PSU), that seems to be cutting it really close to me, will that maybe be a problem?
As for not giving enough info on my specs I have:

CPU: 3.8GHz quad core processor - http://www.newegg.com/Product/Product.aspx?Item=N82E16819113291
Memory: 1 stick/ 8GB G.Skill
HD: 1 TB Seagate 7200RPM - http://www.newegg.com/Product/Product.aspx?Item=N82E16822148840
Optical Drive: CD/DVD Rom - http://www.newegg.com/Product/Product.aspx?Item=N82E16827151258
Motherboard: http://www.newegg.com/Product/Product.aspx?Item=N82E16813128553

I notice that PSU's are on sale @ newegg and i can still actually return the one I bought, with it being that close should I just go ahead and buy a 600w PSU (because isn't a 80 bronze only guaranteed 80% efficiency so I probably am not getting the full 500 W?) thanks!

 

[swilczak]

Your current power supply will work fine, but a couple of years down the road you may have problems since the capacitors degrade over time and you will lose some performance. So you could either stick with the one you have and upgrade a couple years from now, or buy the 600 watt and future proof your PC. You aren't getting the whole 500 watts, but newegg might take that into consideration when you calculate your system specs in their caculator, I'm not too sure.

 

[kearon]

Best answer selected by kearon.