E8400 or 720BE

Depends on your budget. $28 could be the difference between a very good CPU cooler or a nice quality wattage PSU.

E8400 will most likely clock higher, 4ghz or higher. While many of the 720BE, has been reported maxing around 3.8ghz, but you get the extra core.

Testing has shown that 3.8ghz is the sweet spot for most CPU.

It comes down to the motherboard choice, Intel or AMD.

Both are good. But i'd go for the E8400, IMO its the better CPU even if its only Dual Core.

I'd swing the other way and grab the 720BE.

What will you be using the PC for?

I assume you're upgrading mobo at the same time?

I'd go for the 720BE. Good overclocking ability, and the extra core is quite nice.

+1 for the X3 720...
The performance is very much comparable to the E8400 in games and better in most of the multi-threaded apps...

720 BE + AM3

go for the 720BE

I have wondered the same question. I'm trying to read into the Phenom II's a little more. They look promising. In rebviews the 720 looks like to beats out the e8400 in non-gaming apps for the most part. However, the e8400 seems to beat out the 720 in games, I'm guessing because of the higher clock.

What are we looking at for motherboard costs for the 720? Since they both use the same RAM, that's not an issue.

Depends.

If you want an AM3 mobo + DDR3 RAM, you're looking at anywhere from 110 to 140 for the mobo and about 60 for a 2x2gb set for DDR3.

If you don't mind AM2+ mobo and DDR2 RAM, you can grab a mobo for 90-110 and 2x2gb of DDR2 1066 for about 50, or less if you get DDR2 800.

ram is so cheap on you side of the pond  

I know, if the pond was smaller I'd swim but don't think I'll make 3000 miles, could manage 3000mm  

There's an instant rebate of $20 for 720/AM3 combos on Newegg.

^
I can see why its a good alternative to the i7. The total system cost is really decreased. However, AMD doesn't support SLI any longer does it? I know I really wish my last mobo supported SLI, but it was crossfire only. That was one of the reason's I went i7 and the x58 board. I was willing to pay the $230 for the mobo though, but if I couldn't I guess the AM3 would have been the next best thing.

+1 720 BE.
it has 3 cores, it just has to win this one.

The 720 has similar performance per clock per core, similar stock clocks, similar OCing ability, generally better midrange motherboards, has an extra core, and is cheaper.

The key is what will you be doing with this computer? If you use apps that utilize the third core than go for it and get yourself the x3. If your just gaming get a different core 2 (ive got an e7400) with a higher mulitplier for overclocking. If you dont plan on overclocking alot then get yourself an OEM 9950 which will easily go to 2.8-2.9GHz for about the same price and has the addition of a fourth core and isnt built from defective quads. see: x3 series.

I REALLY hope you're not telling him to get a first-gen Phenom. They're terrible compared to Phenom IIs. I believe I saw a benchmark somewhere where the 720 beat all of the first-gen quad cores, despite having 1 less core.

@OP, I'd take the 720. While the E8400 has higher clocks, the 720 has an extra core to run all of the background programs, leaving 2 for nothing but gaming. It also outperforms the E8400 in programs that take advantage of more than two cores.

Get the PII X3 720. For less than the E8400 it's a steal. I do not know why Intel dose not price cut their C2D CPU's.