CFX Fury X PCI-E lane requirements

N4CR

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Was weighing up Skylake or Halswell-E, for a 4k productivity/gaming rig, aim to build in the next month or so, when I decided it would probably help to hear it from the horses' mouth. Grabbed the Fury X user guide, noticed that AMD recommends the following;

'These recommendations apply to both single-card and dual-card installations:
• PCI Express-based PC with at least one ×16 lane graphics slot available on the
motherboard'

Interestingly, that's the very first recommendation they make, without specifying what the second card should run at.

Anyone know of any benches between 16/16, 16/8 CFX Fury X setups? Or anyone with CFX Fury X keen to try?

Failing that, does AMD still have a rep here?

I'm apprehensive to cut corners with the 5820 or Skylake-S, owing to the fact that the Fury X does things a little differently, e.g. with shared pool CFX and 4Gb HBM, that both cards having a 16X lane, may become vital in near future. I understand AMD has already partially answered this question, but for 5820 vs 5930 price, really wondering if it's a matter of a percent or two if at all (as with traditional multi card), which then I'd rather put towards other parts.

Rig is primarily for video editing/content creation, laser programming, R&D, gaming, movies, etc.

Thank you [H]
 

ccityinstaller

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If you are going to go with just 2 cards, and a single PCI-E SSD, soundcard etc, then just grab the 5820K..Save the money vs the 5930K and put it toward more ram, etc...
 

x3sphere

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cageymaru

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I saw in an interview with Huddy that AMD drivers use the system ram to swap textures out. So make sure that you have enough system ram in your next build to account for this. I haven't seen a review where they test DDR3 1600 on old platforms vs say 3000 on the x99. Or varying amounts. But since the AMD guy didn't seem to have a reason to lie, then I would splurge on some faster ram.
 

N4CR

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I saw in an interview with Huddy that AMD drivers use the system ram to swap textures out.

This is what gets me wondering about x16 lanes, throughput and latency differences if any for the application.
Hadn't really considered the RAM speed, as it is generally moot in the post A64 IMC revolution, but now may have a reason to look closer.
Another thing is latency, DDR3 sometimes has an advantage..

Bit of a rabbit hole.


x3sphere, thank you, this is interesting to see and at least something to begin with!

ccityinstaller, this would be my preferred course of action if there is no advantage with the Fury specifically.


Will try to find someone at AMD who knows the answer and report back. Cheers.
 

bob616

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Go with the 5930 then you won't have to worry. Yeah it costs more but the peace of mind is worth it. Or my thinking was: well I could always upgrade in the future, but by the time the 5930 drops in price enough to justify ditching the 20 then something even better will be tempting me to build a new system (and I usually try to keep my system for 5 years but that still applies as the 30 would have to drop a lot in price). Plus there will the temptation of x4 or x8 SSDs in future or who knows what.
 

x3sphere

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So, there's a YouTube channel that did a comparison of a i7 5930K vs i7 4790K with 980 Ti SLI and results are quite interesting -

https://www.youtube.com/watch?v=ZABt8bHgDHo

With both CPUs at 4.7 GHz, you would think there wouldn't be a bottleneck on the 4790K - especially at 4K - but Crysis 3 and GTA V are showing gains of ~20-25% in favor of the i7 5930K! I hope more sites start looking into this with the newer cards, I wonder if the increased PCI-E bandwidth is giving the 5930K its edge here.
 

N4CR

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Thank you x3sphere, great info.

Here is the answer from the horses' mouth.

Amdmatt @ amd forums says;

You will have no issues running 2x Fury X on either X16 or X8 PCI-E 3.0 lanes. In addition, you will be fine using X16 or X8 PCI-E 2.0 lanes. More bandwidth is of course always better, but the differences are still small.

If you're going to be gaming at 4K or higher, then X8 PCI-E 3.0 - X16 PCI-E 2.0 as a minimum makes sense, otherwise you'll be fine with PCI-E 2.0 X8.

TLDR: 4k Fury X wants PCI-E 3.0 X8 or X16 at minimum.


Although I wish I didn't see the 5960 real world improvements for video editing... now I can start 'taping out' the build.. yay. Full CNC case coming up next. The wonders of living in a factory for 5 months!
 

LigTasm

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Running my Fury at x8 on Z97 right now at 4K and I have no issues, it trades blows with a 980 overclocked to 1540mhz at 4K so I'll assume not having an x16 slot isn't hurting it.
 
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