ASUS Z97-A/USB 3.1 motherboard, is it worth it to use 3 GTX 970s for Iray rendering with Daz Studio?

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BigLouis1971

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Aug 23, 2013
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Actually I have that board with a i7-4790K cpu and GTX 970 video card. I want to reduce my rendering times and I'm thinking about adding two additinal GTX 970s. When I cheched the specs of the board I learned that it has 2 PCIe 3.0 slots running at 8x and one PCIe 2.0 slot running at 2x. Will it be worth it to add the two additional video cards knowing that they will run at 8x8x2? I'm a little bit confused because most of the Z97 boards that I checked run at 8x4x4 and I'm thinking there's a typo in the Asus website. Can you confirm that as well?
 
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pebbleberries

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May 17, 2016
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The problem is every time you add a card, the gain is lower. (Hard to explain)

I would go with a more powerful card.

Sell the 970 and get like an nvidia 1000 series.

How much do you want to spend? (American money)
 
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basroil

basroil

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Oct 19, 2013
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That motherboard doesn't even properly support 3x GPU, the last x16 only runs at 2x, which will significantly limit the performance of the last card! Since we're talking about iray and not games, the performance won't be +50% for second and +10% for last card, closer to +90% for second card and +50% for last

Why not just add a single 1080 instead? Same price more or less, much higher performance in iray
 
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photonboy

photonboy

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Jun 20, 2006
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https://www.pugetsystems.com/labs/articles/NVIDIA-Iray-GPU-Performance-Comparison-785/

See if you can decipher that.

It does scale up, but due to your motherboard PCIe allocation I don't recommend more than 2x setup. It's also important to consider:
a) system memory amount
b) SSD (any bottleneck in read/write?)
c) other tasks (do you game?)
d) other rendering programs (likely scale differently)

I don't know your budget, but a 2xGTX1070 is likely as high as I'd go. The GTX1080 is only 25% faster, but you might only see a 10% gain for a lot more cost.

Other:
*Note the loss of performance using "x8" mode. It doesn't matter. It's less than 1% difference.
 
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photonboy

photonboy

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Adding another GTX970 may enable you to render in about 65% of the time. I had to estimate based on the Titan X (120s for one, about 80s for two).

It drops to about 55% for three cards, but again you have a bandwidth issue for the third slot. You'd gain a small amount (5% ?), but then you've got more noise, heat and possible conflicts with games and other software.

1xGTX1070->
If we substitute for the GTX980Ti or Titan X (M) then very roughly it's likely you'd get 20% faster with 2xGTX970 compared to 1xGTX1070.

2xGTX1070 vs 2xGTX970 should mean 20% faster. I just used the chart and again substituted the GTX980Ti or Titan X (M) values.

(I may have made errors somewhere, so run your own calculations).

Again, analyze the chart but also factor in budget, other things like games etc.

Long story short is you may find another GTX970 for $250 or so. Your rendering may happen in 65% of the time. If you bought 2xGTX1070's for $900USD I don't think the time savings are worth the cost.

2xGTX1060's don't appear to be much different from 2xGTX970's which makes sense since they game roughly the same.
 
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BigLouis1971

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Thanks, that's precisely what I needed to know, if the gain is lower everytime you add a card I'll drop the idea of the 3 cards. Now I can return to my orinal plan, have two PCs with 2 cards each, one for rendering, the other one for gaming. What I'll do first is get a GTX 1070 and put it along with the GTX 970 for rendering. That way I'll have 2 cards for rendering and the GTX 1070 for gaming with the GTX 970 for Physx. Then I'll get a new i5-4690K and move the GTX 970 to that new PC and use it for gaming and leave the i7-4790K with the GTX 1070 for rendering. Then get another GTX 1070 and finally have 2 cards for rendering. Lastly I can get another GTX 970 and use it for gaming. I need to do this this way because of limited budget.
 
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photonboy

photonboy

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If it all makes sense to you, then good...

You may want to consider an AMD Zen setup depending on the value later, as well as investigate the CPU importance, especially if you do more than just render with this program.

Zen 8C/16T are going to be expensive. No pricing given, but it apparently should match Intel's $1800USD CPU so I can't see it being too cheap. Their 6C/12T may be reasonable, but we just don't have much info yet and may not for several months.

I wouldn't advise a 2xGTX970 for gaming though. Depending on when you upgrade, maybe just SELL the GTX970 and put that towards a single GTX1070 (or possibly an AMD RX-490 depending on what's going on later with pricing).

Other:
PhysX for an addon card is usually pointless. Not many games support PhysX, and the benefits often are under 10%. Personally I'd just rather yank it out.

It should help a lot with Batman AK. Possibly by 20% (though a GTX1070 should run it nicely already).
 
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BigLouis1971

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I won't use the 970 for physx because I want to, I'll have it because I'll eventually add it to another PC and it'll be more useful as a physx card than in the closet. I don't want to sell it because it still has life and I mostly play in 1080p and I'm happy with it's gaming performance. If I decide to play newer games or play in 4K, I can add another used one for a fraction of the cost of a new 1070.
 
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