VRAY slow on AMD FX8350

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Old 04 April 2013   #16
I would try to strip the scene down bit by bit. Maybe it is possible to determine what part of the scene / function / material whatever causes the difference. After that i would get in contact with the Vray guys and just ask them what to do, or maybe tuning/changing that part will already resolve your speed problem.
It is quite possible that a tiny difference in how the CPUs work can lead to a huge time difference, it just isn't very common or probable.
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Old 04 April 2013   #17
I don't know if it's the case for the software in quesiton, but I've seen more than once cases where AMD's divergence from intel around SSE4 and some of the crippled AVX adherence could deal a pretty solid blow to AMD CPUs, even the bulldozer gen that caught up at least to most of it.
It'd be something to ask the vRay guys though, not here, and I doubt it applies.

That said, I don't know what you expected, the 8150, when it came out, was generally elected as one of the most disappointing CPUs around, struggling to match i5s, and always considerably behind the i7 2.6k.
Even the fabled "stronger on heavily and efficiently threaded tasks" where it was supposed to be architecturally superior to HTing in i7s fell flat on its face everywhere I saw it benched or used.

The 8350, for all the marketing speech about what cores do what and how, isn't much less disappointing.
Your friend has a slightly multiplier OCed 2.6k it seems, and in all honesty, I would expect it to at the very least match an 8350, if not in some instances beat it outright.
You have more ram, but unless heavy paging (let alone swapping) occurs, that doesn't make your computer better than his.

It all doesn't warrant a 250% render time, that might be a mix of several things, but I wouldn't expect an 8350 to leave a relatively recent i7 in the dust at anything.
The marginal advantage you have on the shorter renderings is pretty much all you should expect.
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Old 04 April 2013   #18
here's some data about the FX8350 vs 2600k i7

http://www.anandtech.com/bench/Product/287?vs=697

Be sure to read the charts where is says "lower is better" vs "higher is better"

The 2600 is pretty much always faster with a few rare exceptions. Anywhere it's slower, its fantastic ability to overclock from 3.4ghz to around 5ghz would easily eliminate the gap. Meanwhile the FX8350 will only overclock from 4ghz to around 4.7ghz so it really doesn't have enough headroom to compete.

Last edited by sentry66 : 04 April 2013 at 04:27 AM.
 
Old 04 April 2013   #19
Thanks everybody.
As I said I can understand little differences, but that he's rendering 2.5X faster than me is too much.
Probably it's a series of causes, I don't know. But I guess is something concerning the textures, since in the benchmark scene (that was without texture) I was faster.

So, if it's the texture, how can he be so faster?
 
Old 04 April 2013   #20
Guys, THE MAIN issue is avoiding, and that is in the BENCH scene, FX-8350 is a little bit faster, so lets say they are equal, but in the real life, much heavier scene, everything is oposite!
....
thats the main topic, I do not know why are talking "what did you want from AMD"?
That is not OK, as the all, even VR and C4D tests, talk that they are the same.
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Old 04 April 2013   #21
you might launch up the task manager and take a look at the threading. Are all CPU's at 100% for the duration of the render? If not, the 2600k will have a massive advantage.

How large is the scene file and textures? Maybe he has a much faster hard drive. Maybe there's some rendering functions that are specifically optimized for the i7
 
Old 04 April 2013   #22
Originally Posted by okmijun: Guys, THE MAIN issue is avoiding, and that is in the BENCH scene, FX-8350 is a little bit faster, so lets say they are equal, but in the real life, much heavier scene, everything is oposite!
....
thats the main topic, I do not know why are talking "what did you want from AMD"?
That is not OK, as the all, even VR and C4D tests, talk that they are the same.

In first place the OP seems OK with the answers he got insofar, so no reason to get too excited.
Secondly, it IS OK to mention what's been mentioned, unless you missed the title of the forum.

As for the main problem, of course it is that, pretty much every one of us who remarked on other things also noted that the 2.5x render time isn't normal, but what would you have people do when the benchmark scene isn't available, or known?

It might be anything. Since it's texture heavy it might be anything between an I/O problem and a missing/mis-implemented instruction in the filtering on vRay's side for AMD CPUs (while the differences between Intel's SSE4 + AVX aren't colossal, there are some). It's impossible for people to say anything conclusive, other than recommending to test things one at a time, and possibly procure other benchmarking scenes to compare on longer render times than a minute (which means little) in various scenarios (with textures, without, high sampling, high filtering and so on).

This is a hardware forum last I checked, not vRay's technical troubleshooting forum, so hardware related answers (which, again, the OP accepted gracefully) is what you should expect. Not solutions to software specific problems.
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Old 04 April 2013   #23
Indeed, it's highly possible it's something as simple as SATA 3 or 6GB/s drives vs. older, 5400 RPM IDE ribbon drives. Difficult to say, and as I tend to stick with AMDs from a price/value perspective, the Bulldozers really don't even have the horsepower of the older Phenoms. This is also evidenced in most benchmarks.

I'm not unhappy with my 8120 at all, since the Phenom 1100T is almost impossible to find anyway, but one would hope their new chips would surpass their old ones. So that is always disappointing, even if one isn't comparing the FX chips to Intel's get.

Getting to 5GHz on air alone is pretty sweet though! The Phenom will not do that for me.
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Old 05 May 2013   #24
GUYS!!!
Something crazy just happened! That maybe can solve everything...
I was with a girl watching a movie, so i setted lower priority to 3dsmax.exe process, and also Set Affinity only to 4 cores on 8.
The CPU was running around 50%, only 4 cores were at 100% and 4 were at 10%/15% for the normal computer routine...
And....
A scene that I rendered before in 34 minutes was rendered in 28 minutes!!! WTF!?!?!

Considering this, I guess that CPU is having problems.
Power problems when 8 cores are used? Some issues on using 8 cores all together? 1 core is bugged?
What else!?!? This is leading me crazy!
 
Old 05 May 2013   #25
Two things come to mind. One, it might be overheating. Two, there might be a bug in V-Ray.
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Old 05 May 2013   #26
Originally Posted by chaosmonger: GUYS!!!
Something crazy just happened! That maybe can solve everything...
I was with a girl watching a movie, so i setted lower priority to 3dsmax.exe process, and also Set Affinity only to 4 cores on 8.
The CPU was running around 50%, only 4 cores were at 100% and 4 were at 10%/15% for the normal computer routine...
And....
A scene that I rendered before in 34 minutes was rendered in 28 minutes!!! WTF!?!?!

Considering this, I guess that CPU is having problems.
Power problems when 8 cores are used? Some issues on using 8 cores all together? 1 core is bugged?
What else!?!? This is leading me crazy!


Nicola
Please add the whole scene somewhere on the free web server like rapid, I really have to test it on my own, as I am also confused.
goto file>save as>archive-zip and include the all textures.
Maybe the LC calculation is probably problem? that happens sometimes.
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Old 05 May 2013   #27
I guess it's overheating... :(
I just noticed that the temperature reach 80° C...!

So what can I do?
I'm using a Scythe Big Shuriken 2 rev Cooler:
http://www.scythe-usa.com/product/cpu/SCBSK2100.html
(it's a low profile because the case is an HTPC)

Basically the specs on that cooler seems to be enough for my 8350.
The case has 4 more small fans, and the air seems circulating fair enough...
P.S. case is a Silverstone GD05:
http://www.silverstonetek.com/product.php?pid=241
 
Old 05 May 2013   #28
Please read the posta above, also, if the CPU is 80C, the problem is solved, it is overheating and throtlling, check the CPU cooler, maybe it does not lay properly on the heatsink of the CPU.
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Old 05 May 2013   #29
Originally Posted by okmijun: Nicola
Please add the whole scene somewhere on the free web server like rapid, I really have to test it on my own, as I am also confused.
goto file>save as>archive-zip and include the all textures.
Maybe the LC calculation is probably problem? that happens sometimes.


Sorry I cannot add the scene, the video is not private, but for a major company.

Have you read the thing about overheating?
I guess that's the problem...
I just noticed on an AMD CPU status, that the Frequency of 4KhZ turns down to 1KhZ when the CPU reach 80° during renders. Then from 1KhZ the temperature reach 60°, then start to grow until 4KhZ and 80° and fall down again...
 
Old 05 May 2013   #30
A quick look at some reviews shows that cooler to barely outdo old intel stock coolers and to suffer particularly badly when the case is small and the air is stale (which seems to be your case).

It's also reviewed as hard to seat properly, so it might be one of two things assuming your case has enough airflow despite the cramped space:
It's badly seated and interfaced, not doing its job to its full potential, or it's plainly not enough for your setup.

This explains perfectly why on short renders you were where you were supposed to be performance wise, but falling behind majorly on a long render where the CPU has time to cook.

I'd remove it, clean it, re-paste it, and make sure it's seated well, and give it another go.
If that still cooks hot, then change it or improve the airflow inside the case.
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