i5 4670k Bottleneck three R9 290x's in Tri-Fire?

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ImperialistMillitant

ImperialistMillitant

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Hello people numbered 0-7.5Billion

If I was was to use a motherboard with a PLX chip and run 3x R9 290x's in tri-fire. Would the CPU(i5 4670k) bottleneck? Or is there any advantage to go with more native PCI lanes on the X79&X99?

The reason is that I may wish to run x3 R9's to satisfy my recently reactivated ego however I do not wish to jump to X99 because this would involve me changing motherboard, CPU and Ram(Absurdly expensive DDR4 as of late). Whereas currently I would only need to change the motherboard if the PLX was viable.

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Imperial Eagle
 
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Eximo

Eximo

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My understanding is that PLX chips will let the cards communicate to each other at full speed, which is good for Crossfire. The bandwidth to your CPU is fixed, though, so the PLX chip won't help you there with any LGA1150 config.

I think you would have someone with the configs you are talking about benchmark for you. Tom's has a few articles that tackle the issue of scaling with PCIe bandwidth and card performance, usually didn't matter all that much with PCIe 3.0.
 
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ImperialistMillitant

ImperialistMillitant

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I sort of understand, is it still worth buying a motherboard with a PLX chip or overhauling the entire platform down the line to Haswell-E when RAM prices become more sensible.?
Is the i5 4670k going to bottleneck the CPU?
Otherwise I will change the motherboard quite soon even though I only have one R9. Hopefully they will come down in price when Nvidia release their new line of cards.
 
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DubbleClick

DubbleClick

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Putting in a third gpu as of right now doesn't yield a big performance increase, but makes multi gpu issues like stuttering a lot worse.
Instead of changing anything as of motherboard/cpu/ram, I advise you to just get one more r9, not two.

As for the 4670k bottlenecking: on such a setup in some games, sure. But is it worth spending $1200 to get 5 more fps?
 
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ImperialistMillitant

ImperialistMillitant

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Im not convinced that an i5 4670k would bottleneck three cards seeing how it performs almost as well as top i7s. Is there something I am missing out?

I'm a bit grumpy now, especially how expensive DDR4 is but a platform overhaul isnt likely to happen for a year.
 
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ImperialistMillitant

ImperialistMillitant

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Isnt a PLX chip sufficient or is there some disadvantage with using it? I find that changing to a PLX motherboard would be far cheaper. DDR4 ram is criminally expensive and X79 appears to be a dead end.

Kind Regard
LiberalPeacekeeper
 
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RobCrezz

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You would need to check the reviews and benchmarks of that particular board (with the PLX chip), some work quite well, others less so.

If you can pick up a X79 bargain now that x99 is out, I would go for it, the 6 core 3930k and 4930k are still superb chips.

 
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ImperialistMillitant

ImperialistMillitant

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I like your thinking, I can reuse my ram but the processors are still expensive and most boards only have a few Sata3 ports. I could go for a PCI option?
So much to think about.
 
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DubbleClick

DubbleClick

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You seem to be scared of a bottleneck so much, you probably didn't read my last sentence. The I5 4670k will bottleneck three r9 290's. But by what? Not much, maybe 5-10 fps. You will be in a framerate area past 100 and unless you're using a special monitor with more than 60hz, you wouldn't be able to see any difference, at most on a sneaky fps counter.

There are two real problems here.
First is the limitation of 16 pcie lanes on z97. In a 3 way setup you would have one card running at 8x and two at 4x. Now, if you used an m.2 ssd or something else with a pci connector, all cards would run on 4x. With x99 and a 5930k ($500, DDR4 doesn't seem that expensive anymore, huh? let alone a $450 motherboard) you could run two at 16x and one with 8x, enough.

The second problem is that 3 and 4 way setups are simply not "viable" as of right now. Unless you use 1/2 of them for external calculations only.
Read some reviews and you always see the same conclusion. While adding more gpu's brings more fps, often with diminishing returns, the problems they bring overweight. I can't imagine you want to have your screen freeze for a bit once in a while, a section going blur for short or whatever else miscommunication may happen with 3 way crossfire. Remember early 2 way SLI/Crossfire? Resulted in an unenjoyable mess. Two way sli has been improved to a point that you can use it without worries as today. Three way crossfire has not. Not yet.

Conclusion: Save yourself the money all together, get another r9 290 and be happy with that. Additional $1500 will give you better framerates in some games, but also causes issues you don't want to suffer under.
 
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RobCrezz

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Or just sell the 3 290x, and get 2x 295x2 ? :D
 
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ImperialistMillitant

ImperialistMillitant

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I wanted to use a PLX motherboard which would give the the cards more lanes. Also I am running a resolution 5760x1080p so the likes of crysis could do with more power.

My current specs are listed, if an i5 would bottlneck the three cards then why would they manufacture motherboards such as the gigabyte Sniper 5? If i7s and i5s perform roughly the same in games then why would an i7 all of a sudden pull itself out of bottleneck phase?

@RobCrezz

I dont want to sell my GPU as I will make a loss selling it. I dont want to spend that much, I was under the intention of buying the next GPU's with 6 month gaps.

Regards
Liberal person
 
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DubbleClick

DubbleClick

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It would give your cards more pci lanes to use, but the cpu won't magically start giving more than 16. Thats why multi gpu benchmarks are always done on x79/x99 systems were the cpu allows for more pci lanes. And even there, the third gpu adds less than the second (and produces issues) and the fourth isn't even doing any good for a lot of stuff.

I can link you some german reviews on it. Trying to find english ones, google nevertheless gives me german ones.

And yeah, i5's and i7's perform roughly the same. Not exactly the same. If theres a processor that gives better results than the i5, the i5 is a bottleneck. However, as I stated several times, it will not be by much, probably a few frames per second on average.
 
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ImperialistMillitant

ImperialistMillitant

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Okay that has cleared pretty much everything up for me. Thank-you very much I think I will purchase a second GPU soon and when the opportunity arises for a third, I will just overhaul the platform to X99 in 6 months time perhaps? This should hopefully give AMD MORE time to improve tri -fire drivers. Eventually DDR4 prices will come down otherwise I will vent my wrath at something.
Absolutely no way in hell am I spending £200 on RAM! Especially during the reign of sandy bridge where 8GB could be had for £30!
 
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DubbleClick

DubbleClick

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Exactly what I would be doing. DDR4 RAM isn't that expensive anymore, though. You can get 16GB for ~$250, while 16GB DDR3 would cost $160.
 
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