CPU Upgrade for the Green Gamer

[Onus]

I've been testing RC7 on a machine I call the "Green Gamer," as it was designed to use very little power, just to see if performance would be good enough. With its 4850e CPU and HD4670 GPU, and an Earthwatts 380W 80+ certified PSU, running 24/7 I've seen no notable change in my electric bill.
I am sufficiently satisfied with it that I intend to use it for more and more things, in addition to its primary role as a Teamspeak Server. Since I play mostly older games (Guild Wars, UT G.O.T.Y., DiabloII, even some 2D stuff), the HD4670 should remain sufficient. The CPU, however, struggles a little as it is, and will not be enough for full time use. Maintaining the overall theme of this box, I've arbitrarily decided to limit the CPU TDP to 65W, and it will most likely not be overclocked. If I want to do something that needs more power, I'll use my Q9450.

I've reviewed various CPU charts, and Cleeve's latest article on CPUs for gaming. I believe the 705e should be sufficient. I've only seen a few benchmarks comparing the 705e to the 905e, and they aren't conclusive. Does anyone have any comments on those two? Is the extra core worth $65?
The mobo is an ASRock 790G AM2+, which has 4GB of RAM on it.
Thanks for your comments.

 

[Proximon]

You can just underclock anything you know

The 720 costs less, just get that and clock it down.

 

[hunter315]

if you undervolt it too you may even be able to get better results than the 705e will give you. Im not sure if they pick out super low leakage parts for the low power ones but they are likely pretty close.

 

[Onus]

Hmmm, underclocking the 720BE might make sense, I hadn't considered doing it that way...and you're right, it IS cheaper...

 

[huron]

Excellent suggestions. I think a lot of us forget you can turn them down from max settings.

 

[Onus]

I think that's what I'll do. 720BE it is, turned down when not needed.