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Core i5, AMD 7870

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June 4, 2012 8:34:04 PM

I've bought an AMD 7870 and i'm pairing it with an intel core i5 3450. If in the future i decided to add another AMD 7870 to the system would they be bottle necked by the processor? Also the 7870's are factory overclocked wind force graphics cards by gigabyte.

More about : core amd 7870

June 4, 2012 8:39:38 PM

If you think of adding a second GPU down the road, I'd say play it safe and save money on the 7870 and get a 7850 to get an i5 2500k or 3550k. If in the awkward case that the i5 bottlenecks the dual GPU set up (you'd have to get another 7850 instead of another 7870, though), you can get extra hertz with almost no effort to reduce the effect of the bottleneck (if any).

I don't know what's near the price range of the 7870 nor the 7850 to know how much you'd save and how much is the price difference between the 2500k/3550k with the 3450.

Cheers!
June 4, 2012 8:46:48 PM

It's a tricky question. In games, the 7870+3450 will outperform a 7850+2500k or 3570k. That's because most games are far more limited by the GPU than by the CPU. And the 3450 is no slouch of a processor.

However, if you're willing to overclock, the 7850 is a better value card than the 7870, since it's very overclockable to achieve most of the 7870's performance (actually, more than the 7870's performance, but if they're both OCed, the 7870 will still have a lead). And the 2500k/3570k is also a better value if you're willing to overclock. It's only a few bucks more than the 3450 but will really ramp up performance.

The other consideration is that for its price, I don't think the 7870 is well-positioned. You're better off making the leap to a 670, which has considerably better performance, or relying on the significantly cheaper 7850 with an overclock.
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June 4, 2012 8:50:05 PM

I haven't seen any tests for that scenario but if your playing at 1080p or higher resolution I would not think that the i5 3450 would be a bottleneck to a 7870 crossfire solution.

With that said I would look at the 2500k or i5-3570K for the overclocking headroom just to be sure. The 2500k is the same price as the 3450.
June 4, 2012 9:53:09 PM

i just bought the same pc with a biostar tz77a, and i can warranty that IB wont be bottleneck at all.

Of course u are gonna get a little bit FPS bellow an overcloked i5 3500k at 4ghz but for 4 or 3 fps that wont matter, especially on 1080p were the 7870 is a beast... i hope u are thinking on the future, i mean like there is no sense on buying 2 of these right know, with that money u could buy a 680gtx and have like 100$ left. :D 
June 4, 2012 10:01:25 PM

I should add that the fps difference will vary based on the resolution and the game. In general, higher-res gaming adds much more workload to the GPU without marginally taxing the CPU as much. So higher-res gaming is more GPU-limited. There are also certain games (SC2, BF3 multiplayer) that are more CPU-governed. But I don't think you'll experience much CPU bottlenecking even in crossfire, especially if you overclock to 3.9GHz (which you can do--4 bins higher than max turbo).
June 4, 2012 10:48:04 PM

Depends how demanding the game is, but right now the majority of games would be bottlenecked by the CPU with a 7870 at 1080p. There's definitely very demanding games out there that will push the GPU, but most games aren't that brutal.

If planning a second 7870, the only benefit would be if you are also buying a bigger monitor like 2560x1440/1600, or are going 3D, or multimonitor (5760x1080). Or any combination of the prior.
June 5, 2012 4:38:50 PM

I've decided to go with the i5 3450 and one 7870 since i'm only gaming at 1080p, how long do you think they will last before i need to upgrade again?
June 5, 2012 5:28:53 PM

Well, it depends mainly on new tech for games coming out from E3 that has to be announced.

I'd say that in the low side of estimations, a good 3 years. That's the minimum I'd put my hand on fire for. I had the 4890 for 4 years and it was just a mid-range card (under the GTX280 of the time), just like the 7870 you're getting. Replaced it with a GTX670 just last month.

Cheers!
June 5, 2012 5:34:27 PM

Did you actually buy i5 3450 already? Because i5 2500k has just so much more performance/price ratio.
June 5, 2012 6:05:12 PM

If you could list some of the games that you plan on playing, it would go a long way in helping us help you. However, I've never heard of an i5-3450 bottlenecking anything, and according to the latest Hierarchy Chart for gaming CPU's, http://www.tomshardware.com/reviews/gaming-cpu-review-o..., the 3450 is in the top tier when it comes to gaming performance.

Unless you play the latest and greatest in GPU-eating titles, or are an FPS-whore :D , you can't go wrong with the 7850 or 7870 set-ups.
June 5, 2012 6:11:06 PM

Really depends how much of a graphics whore you are. Pushing games to the extreme settings can take a LOT more power than high settings with IMO fairly minimal differences in looks.
June 5, 2012 6:20:13 PM

I've not purchased the processor yet. I'm buying all the other parts for the PC tomorrow, I don't really want to spend anymore then i have to upgrading the processor as the total cost of this build is already around £900-950.

The games i will be playing are :

Battlefield 3

Company of Heroes

Total War - Shogun 2

Mass Effect 1,2 and 3

Skyrim

Fallout 3/New Vegas

Left 4 Dead 2

Age of Empires

GTA 5 (when it comes out)

I want to be playing the games on high settings so they look nice, hopefully that will give you an idea of the games I will be playing.

June 5, 2012 6:25:39 PM

I can list the full build spec if that helps?
June 5, 2012 6:48:49 PM

Do that!
June 5, 2012 7:08:13 PM

Well, BF3's multiplayer and GTA5 when it comes out might want a little more potent CPU than the 3450.

Other than those, I don't think you'll notice a difference without doing a really big OC on the 2500K.

But I do agree, the 2500K is the better buy if they cost the same.

Cheers!
June 5, 2012 7:25:40 PM

The 3450 and the 2500k aren't the same price the 3450 is £22 cheaper.

The full spec of the computer is:

Blu-Ray Reader for PC from LiteOn IHOS104-32

650W Corsair Enthusiast Series TX650M Power Supply

Corsair Air Series AF140 Quiet Edition (I'm buying 4 of these to replace stock fans on the case and add one more.)

Gigabyte GA-Z77-D3H Intel Z77 Socket 1155

60GB SSD Corsair Force Series 3 Series SATA III - 6Gb/s Solid State Drive

Intel CPU Core i5 3450

Seagate 500Gb 3.5" Barracuda Hard Drive 7200rpm 16MB Cache

Corsair Memory Vengeance Blue 8GB DDR3 1600 MHz CAS 9 XMP Dual Channel Desktop

Gigabyte ATI Radeon HD 7870 OC Windforce 3X 2048MB GDDR5 PCI-Express Graphics Card

As I've mentioned i'm buying the parts and building it tomorrow with a friend, this is to be my first build so i'd like to get it right with the parts. If there is anything i should change or improve could you please tell me.

- JNB
June 5, 2012 7:27:40 PM

Oh, I forgot to mention the case is :

Corsair Obsidian 550D Black Mid-Tower Computer Case
June 5, 2012 7:30:50 PM

Sounds like a solid build, mate.

Tell us how it performs once you build it!

Cheers!
June 5, 2012 7:34:37 PM

Thanks i will, about the processor if it's really needed i could push the budget for the top end 3570k but i have no clue how to overclock.
June 5, 2012 7:39:10 PM

You really don't need a faster processor. Very few games are so CPU-sensitive that they'll notice much difference between a quad-core 3.5 GHz Ivy Bridge and a quad-core 4.4 GHz Ivy Bridge, or whatever else you might OC to. As I mentioned above, you can also overclock your 3.5 to 3.9, even though it's multiplier-locked. Your money is better spent on the video card.
June 5, 2012 7:41:42 PM

What do you mean by multiplier locked? Also i have already ordered the graphics card so i'm hoping it will be good enough for my needs.
June 5, 2012 8:02:11 PM

"multiplier-locked" means it's not a -k series processor, which are "unlocked," i.e. you can overclock them freely. On a k-series Sandy Bridge or Ivy Bridge, you have a lot of freedom to change the CPU's "multiplier," which determines its maximum clock speed. For example, a multiplier of 37x on a typical i5 or i7 means a speed of 100MHz*37 = 3.7GHz. (The 100 MHz in that calculation is the BCLK, which you don't have much control over in sandy or ivy bridge.) But to overclock, people ramp that up to (e.g.) 45 or 47, so 4.5 or 4.7 GHz.

Even locked SB and IB processors can have a small overclock, though: you can set the multiplier to 4 steps higher than its maximum turbo frequency. So for example, on your 3450, the maximum turbo is 3.5 GHz = 35 multiplier. You are then able to set a multiplier of up to 39 = 3.9 GHz. That's not insignificant (more than 10%).
June 5, 2012 8:12:12 PM

How would i go about doing this when i have the computer? Is there specific software i need? Also I've heard people talk about voltage when overclocking, what is that about?
June 5, 2012 8:15:41 PM

I'd get one fan less and for that price get i5 2500k instead of i5 3450. Why do you need case fans anyway? Get an aftermarket cooler for the CPU instead :) .

I'm just trying to make your build faster, you may take or not take my advice, that's your choice.
June 5, 2012 9:10:16 PM

motorneuron said:
"multiplier-locked" means it's not a -k series processor, which are "unlocked," i.e. you can overclock them freely. On a k-series Sandy Bridge or Ivy Bridge, you have a lot of freedom to change the CPU's "multiplier," which determines its maximum clock speed. For example, a multiplier of 37x on a typical i5 or i7 means a speed of 100MHz*37 = 3.7GHz. (The 100 MHz in that calculation is the BCLK, which you don't have much control over in sandy or ivy bridge.) But to overclock, people ramp that up to (e.g.) 45 or 47, so 4.5 or 4.7 GHz.

Even locked SB and IB processors can have a small overclock, though: you can set the multiplier to 4 steps higher than its maximum turbo frequency. So for example, on your 3450, the maximum turbo is 3.5 GHz = 35 multiplier. You are then able to set a multiplier of up to 39 = 3.9 GHz. That's not insignificant (more than 10%).


Is there any way i can permanently turn turbo boost on so it's always running at 3.9 Ghz?
June 5, 2012 9:35:15 PM

Well, by default your max turbo setting is 3.5 GHz on the 3450. But yes, in the BIOS, you should be able to bump that up to 3.9 GHz.
June 5, 2012 9:43:33 PM

Not one of those games is all that CPU intensive - for gaming I have all three of my 6950s running and they're not bottlenecked at all by my 8150, and a 3450 is quite a bit better for gaming. I wouldn't worry about it at all.
June 5, 2012 10:54:11 PM

Just throwing it out there, 60gb is just barely enough to hold an OS with a few more programs. I have very few programs, the biggest ones being probably Photoshop and... iTunes, and use just over 60gb of my 80gb drive. On top of that, you actually end up with a bit less than 60gb usually. So basically, tread cautiously there. I would suggest not getting the SSD right now and wait until you can afford a 120gb, or at least an 80-90.
June 5, 2012 11:13:21 PM

How much space does Window 7 Ultimate 64 bit use?
June 6, 2012 8:16:28 AM

Around 35 GB with all updates.
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