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I just bought a new gaming rig and and I had to go on the cheap for much of it (as I had to squeeze new winter tires, new hockey equipment and house taxes) in there, so I went shopping on a budget (but splurging on a 7870 Ghz edition and SSD's as those I think would make the biggest difference to my budget gaming machine. I bought a:

core i3 3220 (3.3Ghz)
MSI G41 Z77 motherboard
Radeon 7870 Ghz edition
plus a bunch of other stuff not relevant to this question...

I figured the price difference between the core i3 ($109.99) and core i5 ($179.99) wasn't enough to justify the little bit of "turbo" the core i5 offers, but then I saw that apparantly the i3 only supports PCI 2.0 http://en.wikipedia.org/wiki/Ivy_Bridge_(microarchitecture)

Hold on a minute, that's a pretty big deal. Does this mean that my shiny new Z77 motherboard would only be running it's PCIe 16x in 2.0 mode? If so, would that have any impact on my 7870's ability to output graphics? I looked through TR's review of Ivy Bridge but they only tested i5/i7. I Haven't been able to find anything on the net to give me a solid answer, but I'm still looking.


If it will impact performance, I'll buy an i5, but I'd rather save the money...

cant speak to the pcie difference, but you got a dual core instead of a quad core. that's the chief difference.

dual core with HT vs quad core without

still 4 threads, but the i5 should have significantly better performance i think.

In games, an i5 will be better than an i3, but only marginally. Your i3 will still outgame almost the entire AMD lineup. The only time an i3 has problems is in applications that can take advantage of more than 2 physical cores. (HT does help a little, but it's DEFINETLY not like having 4 physical cores) Things like video encoding, Adobe Creative Suite products, file compression, etc can significantly benefit from more cores if you're doing large files/projects. Since your build is focused on gaming, I doubt the time savings in these programs is worth the added cost.

Regarding PCIe 2.0 vs 3.0: Even a 7870 can't saturate 16 lanes of PCIe 2.0, so you're ok. The real benefit to PCIe 3.0 having twice the bandwidth right now is for the mobo manufacturers to split those higher speed lanes more ways without a tangible impact on performance. This means more bandwidth flexibility in today's high speed interfaces (ie Crossfire/SLI, USB3.0, Thunderbolt, etc).

PCI 2.0 has enough bandwidth on the bus interface that no GPU or game out today is able to fully saturate it. You usually find a bottleneck in your system elsewhere first, so I wouldn't worry too much. This was much the same when AGP got various speed bumps - In the real world it made a non-discernible difference on gameplay.

IMO, you'll be able to overclock the GPU's memory a bit and it will you a 2-5 extra FPS. Maybe an additional 1-2 FPS bump if you overclock the core too, but it doesn't do nearly as much to the performance like the memory does - If your worried about performance.

*Edit: The [H] has a good review to back this up. Conclusion is that the small 2-5% performance variation is more to do with IB's per-core enhancements rather than the PCI interface type. In many cases there was no differnce at all.
Source: http://www.hardocp.com/article/2012/07/ ... _review/14

*Double Edit: DPete27 beat me to it!

Almost all cards run at maximum, or near-maximum throughput on an old PCIe 1.0 slot (x16) which means that you utterly, totally, definitely don't need a PCIe 3.0 slot

Even if you were to run your card at PCIe 2.0 x8 instead of x16, you'd still get 95% of the performance, and bear in mind that the numbers below are for more potent graphics cards than your 7870:

http://www.techpowerup.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/23.html

Awesome guys, thanks for all the replies.

Yeah, I was thinking the difference between PCIe 3.0 and 2.0 was kinda like the AGP 8x/4x, but I wanted to make sure. I won't ever be doing video encoding, Adobe Creative Suite, file compression or anything like that.