Would a 4.8Ghz E8600 bottleneck a pair of 4890's in Xfire?

Not on most games, no.

Why not use the 920 if you're getting a pair of 4890s though?

If your friend already has the E8600, then its fine...
But like cjl said, the i7 would be the best option rather than the E8600 - Reason -> Some of the current/ future games are/ will be optimized to take advantage of multiple cores(As you can see with the GTAIV and FSX)...

Depends more on how CPU intense it is. At high res, GPUs'll be your money.

4.8 GHz...lawls

Benchmarks do tend to show a benefit for high end CF/SLI setups.

I worry about some people.

You are talking about an overclock that is not is probably not going to happen. Yes, we've seen cases of e8600 on air reaching almost 5ghz but every chip is different and even the best chips require 1.6 volts to reach that clocks. That is something that is not recommended for daily use unless you have phasecooling.
Core i7 offers better performance per cycle and if you demand the highest performance you have to be willing to shell out more.

A single 4890 is able to play most current games at highest settings @ 1650 resolutions. i would not go with that setup unless you had a 1920x1080 monitor or higher and play all the latest games.

I've had two E85's run at 4.8Ghz daily with water so the overclock is realistic for an E8600. It also only takes 1.475v's to reach that speed.

it has been demonstrated that for SLI And Crossfire you see a significant performance boost using quad core systems like the i7. I havnet found any comparisons using SLI and the Q9x50 systems but my guess is it should be similar.

http://www.guru3d.com/article/core [...] e-review/8

I think the key here is to note that at very high resolutions the performance is GPU-bound so there isn't much of a different between i7 vs E8x00, but at lower resolutions where GPU is not bottlenecking the configuration you can clearly see the advantage of the four-core/8threaded processor and the new architecture.

The more GPU power you throw in, the better benefit u'll get out of an i7 build.

But i tihnk in ur case E8600 + 4890 XFire will be fine. if u go i7 u'll probably be looking at only 4890 for the same price as u'll spend extra on the board + RAM + CPU.

and either way, both systems perform really well.

one thing though. Benchmarks with core i7 920 have shown taht the performance boost for gaming when the chip is overclocked increases at a faster rate than it does when you overclock Phenom II X4 9x5 and Intel Q9x50 CPUs. I dont have the link but u shud be able to find it if u google around.

For some, yes, but that is by no means guaranteed. I wouldn't count on anything above 4.2GHz or so (though many do go higher).

+1 on the i7 build or top of the line AMD cpu, why?...
forget about performance for a sec, how about future app's, they are improving and thus must all system to keep up, lets say new games start coming out, just like GTAIV that utilizes all 4 cores, then what?, toss around your dual core and put what, socket 775 is been phase out, and thats just the CPU, lest say you or your friend have more money than Bill Gates and are able to spend all ya want, and replace your rig every year.
With the dual core ya more likely use DDR2 because DDR3 don't have much performance increase on dual cores and then you will be seriously wasting your money, and thats the next thing is been replace, memory, so all around if you have enough money now go with the I7, wont regret it at all, it has the performance you're looking for and a upgrade path as a bonus, I7 is the top of the line and will be for quite some time, why?
because Intel play the cards really smart, they are coming with I5 processors so instead of making something better they are making something less expensive, because there is nothing compare to an i7 when performance is the topic so Intel feels like instead of making better they have to downgrade a few steps because they are way ahead in the future.
Also unless u playing on something bigger than a 32" inches monitor 2CF 4890 are somewhat an overkill but as i say earlier it will also make your rig last longer, although a 1 card solution is better because if needs to replace as need comes up it will be easier, i say if you have the money and performance its all you care about an GTX295 is the way to go.

More info is needed to come up with a good idea, and be able to help further

whats your budget?
where are you buying from? Do you have any retail store that sells computer part close by?
when are you building? exact date
is gaming your only need?

Yeah I'm happily running 4320Mhz on my E8500, 1.42V idle, 1.38V vDroop. Daily setup. Air only, using a Coolermaster Hyper N520 cooler.

I was considering buying an E8600 so I could try and go higher without stressing my northbridge so much, higher multiplier would make it easier. It seems to be the NB/RAM that causes my issues more than the CPU.

But i7 still a much better option. Although with i7 I find the boards are more expensive, the RAM is more expensive, etc. In the end building an i7 system is a lot more than just paying a few extra dollars for the 920!

I also just like the high frequency for what we call 'wank factor'. The idea of a CPU running that many clocks is awesome (to me anyway). Any actual performance increases I'd doubt I'd ever notice outside of benchmarks.

the I7 is a waste of money, if you already have an q6600 you will not see a diff at all if you get a 920, it's nothing more then waste of money, i have friends who have sold the i7 and stayed with the q series, just because it's new dosen't mean it's better

Not everyone has the same wants/needs as you, Croc. If he wants to get 2 4980s, what's wrong with that? If he is financially able to purchase these, and not live in the street next week, how is that senseless?

if u already installed the e8600 then dont worry u will be fine. dual 4890 if played in 2560 resolution is not bottlenecked by e8600 running at even 4.2GHZ. becoz at that resolution u need gfx. i m talking about most of the games that requires huge gfx power than cpu. But yes if u run cpu intesive games specially strategy games like supreme commander, redalert3 then u should get core i7.

I'm sure the OP got the answer already so just select the best answer to make this thread solved. Wasting people's time

If you read correctly, I had written there were 29 pages to view, and requested you start on page 1. You told me to show you "a benchmark". I showed you many, and you still refuse to listen to reason.

You said "significant gain". You never stated significant was anything under 60fps. Significant in this case is almost 40% average gain among all tested games at 1920x1200. An almost linear performance gain is significant. I'm not trying to be arrogant, I just would prefer you to define how you perceive significant so we can avoid this back and forth in the future. It is true that your eyes can not tell much over ~60FPS, that doesn't take anything away from the almost linear FPS improvement. Sure, the second GPU may not be necessary, but the gains are anything but insignificant.

Don't get offended/defensive on an internet forum, it's not worth the time. I understood what he meant, but it isn't relevant to a technical topic, so just let it slide.

Benchmarks of a 8400 are close enough to be interesting. An E8600 will be the same except 10% higher (or near enough to). I expected to see them the same until the resolution went up - but it was the opposite.

I found those results really suprising. I always thought GPU power + bus width made the biggest differences.

I wasn't saying don't post, I was saying it's not worth your time.

Those results are still interesting however.

We pretty much post what we want on here and technically the post amdfangirl quoted is totally contradicting what you first posted to me ?

@ amdfangirl

I was just saying it's not worth the time. I said the same thing in both posts.
But anyway wasn't intented to offend/annoy anyone, sorry about that.

Edit: should point out, language differences, when I said 'Don't reply to'... it was meant as friendly advice rather than an instruction, my apologies about that too, I'll try to be clearer.

lol English is actually my first, I was meaning what we say can be read differently to how we'd understand it here. No excuse I know.

I'm from New Zealand Good work on the 3 languages, if I hadn't seen you mention it, I'd have thought English was your first.