Render time increases with more RAM???

[mailerik]

Hello everyone. i have been a long time lurker on the forum but haven't posted in a long time. I am having an issue i hope someone can shine some light on. I was doing a benchmark rendering comparing the difference in performance with more RAM. When i increased the RAM form 2GB to 4GB my rendering increased 10secs!! I really thought it would decrease but it didnt. heres my setup.

AMD Athlon 64X2 Dual Core 4200 2.21GHZ
ASUS mother board
Win Xp Pro 64
2GB RAM increased it to 4GB
2 Seagate Barracuda 7200 80 GB
(1st drive contains 2 partitions containing windows/paging file area; 2nd drive no partitions all for data)
Max 9 64bit
vray 1.5rc3 64bit

any ideas anyone?? the rendering totaled 8min 12secs with 2GB and 8min 22secs with 4GB of RAM.

[RErender]

Some MB's slow down the timings on the RAM when using more than 2 slots, that or the sticks you added may have slower timings so the speed would automatically be lowered to those for all RAM, maybe that would account for the difference?

You might try manually setting the timings and speed, probaly help to bump the voltage up slightly also.

You should see a large speed increase though on scenes that use more than 2 GB

[mailerik]

ReRender,

how can i manually set the timing and speed and increase the voltage? i've never done anything manual to hardware.

[percydaman]

This section of the forum is for VRAY specific related problems. Please post these sort in the Off Topic section, thanks. Ill move it on over for ya

[RErender]

ReRender,

how can i manually set the timing and speed and increase the voltage? i've never done anything manual to hardware.

The adjustments are made in the bios setup

all bios' are different so without seeing the manual I can't give specific instructions.

It will take a little research (maybe impossible with off brands) but you will want to find the timings for your RAM modules, something like 4-5-4-18 , Some RAM has this on a sticker on the module itself, and their nominal voltage 1.8v or whatever. The timing settings are almost always in the same order in the bios as the timing #'s that the RAM timings are written.

You'll want to set the memory ratio so that it matches your ram ddr400 or whatever you have, I would try to use the timings of the fastest pair of RAM and bump the voltage up .1, see if it runs stable.

If for some reason it won't post (highly unlikely in this scenario) just reset the bios jumper or pull the MB battery for a few minutes and it should post up with the defaults.

While this is not really overclocking it's very likely that someone has done a write up on overclocking your motherboard and CPU, I'd do a google search and see if there's some article that explains where the memory settings are in the bios

[werticus]

i would not bother with ram timings, what you want to do is actually start to USE that extra ram ... 10 seconds slower is nothing when you now have access to twice the geometry than was even possible before.

go to settings tab, and increase the dynamic limit to take full advantage of that ram. Then render a scene which actually uses a decent amount of ram and tell me its slower!

[percydaman]

more ram only speeds up rendering, when it was the cause of render slowdown to begin with. Like others have said, render out scenes that took more then your initial 2gigs of memory, and you'll see the difference. You can't have too much memory these days.

[DaForce]

10 seconds is really neither here nor there. Could have been some program in the background sucking up a few more cpu cycles over the 8mins of the render.

Also increase the dynamic memory limit isnt the best idea as well. Ideally you want to try and stick with static memory now that you have more. As the render will be faster.
Using dynamic is slower but lowers the memory usage.

Mind you proxies/fur/displacemant are all dynamic anyway...so..

And as RErender said, more ram is only need if.. more ram is needed. Ram isnt a performance increaser as such its more of a performance degredation preventer

[mailerik]

great info everyone. i upgraded the ram because i had it sitting in another computer that was down without powersupply. im sure it will be helpful in a more intensive file. thanks again.

[werticus]

thats not 100% true daforce, remember certain functions in vray use dynamic memory regardless of that setting being on static.

such as displacement. and proxies i think. which then look at that setting.

[DaForce]

yes that is true, I did kind of mention that.

But the point still stands if you want your renders quick stick with static as much as possible, sure some things render in dynamic and you may need to increase the dynamic memory limit abit to help those out if your using lots of displacement or proxies.. but you dont want to raise it too far.

Certainly using more proxies/displacement and dynamic memory will slow down your scene.. how much.. depends on your implementation of the proxies. Although is usually in the order of 10% but cant be as much as 50% or even higher if proxies are used wrongly.