Which stepping is the i7 920? The D0 overclocks much better than the C0 stepping.
But if they're the same price (including the price of the motherboard) I'd say go for the i7 920, mine still plays all modern games without any problems. Or if you can find an i5 2500K or 3570K for around the same price then go for those because the 920 is already 2 generations old and a bit of a power hog.

 

Well just a quick glance at passmark to make sure I am correct a Phenom II x4 980 @ 3.7ghz scored 4540, whereas the stock clocked (2.67) i7 920 scored 4947, so we have a quad core with hyperthreading form Intel at 2.67 outscoring AMD's fastest stock clock Phenom II, now as slh28 said the D0 steeping is the best, but both steppings can get the chip over 3ghz, were looking at well into the 5,000 mark now for a score, where as overclocking the phenom II is nice because of the unlocked multi, but that particular architecture usually stalls around 4ghz for a daily overclock so your not gonna see much more out of that chip. If the motherboards are the same price, since X58 used to be substantially more expensive the am3, then I would suggest the Intel, honestly gaming wise though both chips are gonna be great and should be able to handle any game. check out this techspot review, the phenom is a bit lower clocked, but just add around 3-5 FPS in most cases for gaming. https://www.techspot.com/review/195-mainstream-quadcore-cpu-performance/page7.html , but do remember that a stock clocked i7 920 the nehalem architecture loves clock speed, and really shines at higher speeds.

 

This^

 

Intel processors are really hard to beat. I read an article where a 4 core Intel beat a 6 core AMD. For gaming I think the Intel processors are better.

 

and a core i3 beat a 4 core unlocked amd

 

well that would depend on the game, most games are still unfortunately dual core optimized, but I can say after gaming on my friends i3 2100 and then going back to my phenom II x4 that I can beat him in games were quad cores are truly utilized, both of the cpus can take games to well beyond 60 FPS making the choice less about performance and more about cost.

 

yeah definitely

 

I'm going to look for screens of my 920 C0 and D0 in vantage. I'm not going to say d0 overclocks better than c0. Its the voltage required and the heat generated that determine the OC. Both my c/d 0 stopped at about 4.6ghz but I had them both watercooled. 1.41 for D0 and 1.46 for c0. Not that far off.