VRAY slow on AMD FX8350

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Old 05 May 2013   #46
I thought that I told you the case model... It was a Silverstone GD05.

Anyway, I bought a larger case and a new cooler, now there're no more temperature problems!
But renders time are not improved at all!!!
Well, let's say that if before my friend was 2.5X faster, now he is 2.3X faster... :(
Still going crazyyyyyyy!

Here a screenshot of the temperature (note that the CPU from 80 now it's down to 50 even on a massive render):


So, now everything is better and I'm not risking my CPU, but the problem is still there!!!
Almost no improvements on the renders time....

:(
 
Old 05 May 2013   #47
Borrow your friend's computer, maybe?
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Old 05 May 2013   #48
Originally Posted by InfernalDarkness: Borrow your friend's computer, maybe?


LOL! I'm in Finland and he's in Italy... anyway, I like to fight with issues until I found a solution... And this is a big mistery!!!

P.S. I'm redering again a massive scene using 4 cores instead of 8 and it's going faster... even though it wasn't a temperature problem. WHY!??!
 
Old 05 May 2013   #49
Sounds like an interesting issue still. Your CPU has four physical cores and four more which share the memory resources with the first four. In ProcessLasso, for example, you can set the CPU Affinity to "Avoid non-Physical cores", which gives you all the odd-numbered cores and not the evens. I've never had it render faster with just the Physical cores, however, and the scene I'm working on is enormous. I'll give it another test when I get home and see if it's faster with just those four, but thus far the cores have scaled rather linearly. All 8 render twice as fast as just the 4, so far. I'll do a comparison of all four Physicals, then the first four (2 physical, two piggied) and see what that looks like, tonight.

Are all 8 cores being fully saturated when you render with them all? Is your CPU load at or near 100%? Also, what type of hard drive are you using? Data transfers may be bottlenecking you, especially if your friend is using an SSD or something zippy like that.
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Old 05 May 2013   #50
maybe the render sends out packets to each core and the cores with floating point units do great while the other ones are slow and hold everything up? Overheating obviously isn't helping anything
 
Old 05 May 2013   #51
I don't really know what could be...
But for sure when I'm using 8 cores, they are all 100% (or almost), at the correct frequency, as I can see from the AMD Overdrive.
As the 4 cores are all at 100% right now that I'm rendering with 4 cores disabled (50% total CPU usange) and it's faster... a little bit, not so much, but faster! And it has to be 50% slower!!
 
Old 05 May 2013   #52
Originally Posted by chaosmonger: I don't really know what could be...
But for sure when I'm using 8 cores, they are all 100% (or almost), at the correct frequency, as I can see from the AMD Overdrive.
As the 4 cores are all at 100% right now that I'm rendering with 4 cores disabled (50% total CPU usange) and it's faster... a little bit, not so much, but faster! And it has to be 50% slower!!



no, that's not what I'm saying

I'm wondering if it's a similar thing to intel's hyperthreading when it first came out and software treated the virtual cores as if they were real cores, thus making performance suffer when they were enabled. It wasn't until software became optmized for them that they didn't suffer a performance penalty or would use them in a way that sped rendering up

if the FX8350 has 4 cores with floating point support and 4 cores wtihout floating point units, it wouldn't matter if the cores without floating point units are at 100% or not, they'd always be slower at rendering - drastically so

If the render sends equal jobs to each core, the cores without floating point units are going to be handling loads they're going to suck at doing. It could be the rendering engine isn't optimized for the FX-8350 and doesn't understand that it really shouldn't be sending any jobs to those cores, or reduce the job load it expects them to handle.


The issue is probably compounded by having all cores at 100% hitting their temperature limit and throttling. There's probably less throttling by just using 4 cores.
 
Old 05 May 2013   #53
So how can I manage the throttling issue?
I tried already from the bios disabling unnecessary power safe controls...
 
Old 05 May 2013   #54
This is my mobo specs:
http://www.asus.com/Motherboards/M5...#specifications

I'm reading around that the throttling problem could be caused by voltage, bad motherboard, etc...
 
Old 05 May 2013   #55
I tried setting manually the multiplier to 18x and a lower CPU voltage, but nothing...
I tried disabling Cool'n'Quite, C6 and other power safe settings, but nothing...
Still throttling!
It's not a temperature problem (that is around 50). Don't know...
My mobo is not enought? There's something else that I can try?
 
Old 05 May 2013   #56
Find someone with a similar CPU, or benchmarks timed against it that offer the scene, and see if it's simply the architecture that's so inferior, or just your setup specifically and they are fine.

Also test whether it was the textures or the longer rendering times setting you back, the former might have many implications, the latter still points at an unstable/insufficient configuration in terms of handling power and tasking.
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Old 05 May 2013   #57
Originally Posted by ThE_JacO: Find someone with a similar CPU, or benchmarks timed against it that offer the scene, and see if it's simply the architecture that's so inferior, or just your setup specifically and they are fine.


Or if there's a bug in V-Ray... I feel like a broke record here. Contact V-Ray support.
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Old 05 May 2013   #58
What do you mean with "broke record" in VRay?

I have the feeling that is a CPU throttling problem. So something hardware, not texture or whatever.
I can notice that my computer slow down to 7x multiplier and 1000MhZ (instead of 20x and 4000MhZ) lot of time during render. I think it's some hardware issue.
 
Old 05 May 2013   #59
Originally Posted by chaosmonger: What do you mean with "broke record" in VRay?

I have the feeling that is a CPU throttling problem. So something hardware, not texture or whatever.
I can notice that my computer slow down to 7x multiplier and 1000MhZ (instead of 20x and 4000MhZ) lot of time during render. I think it's some hardware issue.


In the BIOS there's probably a setting for throttling the CPU that can be disabled. I'm looking at the motherboard manual right now, it's a ASUS M5A78L-M/USB3, right?
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Old 05 May 2013   #60
Yes, that's the motherboard.
As I said, I've already disabled something... but thank you for your cooperation, if you find exactly the throttling thing to disable would be nice.
 
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