2 560-448 cuda cards -- but no room for expansion...options?

[johnb4467]

Hi everyone,

I've spent quite a bit of money trying to maximize the Octane experience: I "moved out" of my previous mini-itx case, as it could only accommodate 1 graphics card, and was limited in the psu it could take.
I'm now in a mid-tower case with great ventilation, have a 1200 watt gold psu, and two of the msi frozr III 560-448 cuda core cards. The cards run great; they run fairly cool, even under full load...with a caveat to their perofrmance:
The downer in this scenario is, however, that those cards don't utilize stock fans that shoot the heat out the back of the case; they're 'open' fans -- and thus get no breathing room if I butt them up next to each other slot-wise -- in fact, the fans will hit the card next to it! Even this doesn't happen, the cards will immediately jump up to 99 degrees...of which is the maximum allowed temperature -- and I'm guessing not good for longevity.

My mobo is an Asus "Supercomputer" (their title, not mine!) motherboard; it's an older LGA1156-based board, but has a load of PCI-e 16x slots...which I'd love to populate. The most I can fit with 'dual slot' cards is, of course, 3 (almost four -- but no-go). Right now, however, I couldn't put even another 56-448 in there if I wanted, due to the above ventilation / room reason.

My question is this: If I sold off even just one of the 560-448's, I could likely round up 2 used 470 cards. I'd hate to do this, as I love the 560-448's, but I'm curious as to if having one 560-448, and two 470's would actually put me in a much better position rendering-wise? I've built this machine pretty much just for octane, so I figure I might as well try and maximize my performance -- within financial reason, that is.

Thank you for any help or suggestions you might have! Right now it doesn't look like the charts really list the 560-448 cards, so I don't if how much...if any...better they run than the 470's.

John

[steveps3]

I wouldn't expect for you to get any performance increase with 2 x 470s replacing 1 x 560. In fact you may even get a decrease in performance. I have 2 x 560s but not the 448 models and I have a 460 card. The 460 card contributes maybe 20% to the total rendering power.

[JimStar]

johnb4467
With more than 2 cards you will not get normal temps with any air cooler system. I tried it already, don't waste your time.
I wrote already about it HERE after I ended up with config that I have described HERE.
And 1200 PSU IMHO may be not enough for 4 cards config...

[steveps3]

1200 watts will be plenty for 4 cards. I have an 850 for 3 cards and I am still only actually drawing around 450 watts. I could get 4 cards into my system (if I had the PCI-E connectors). No problem with temps either. Running 100% my 560s might hit 70 degrees.

[JimStar]

1200 watts will be plenty for 4 cards. I have an 850 for 3 cards and I am still only actually drawing around 450 watts. I could get 4 cards into my system (if I had the PCI-E connectors). No problem with temps either. Running 100% my 560s might hit 70 degrees.

Do you want to say that if e.g. rest of your system eats even 100W (it must be more indeed), each of your cards eats only 350/3 = ~116.5Watt in full load??? It can't be true. You can see HERE that 560 in full load eats 358Watt. So 3*358 = 1074 Watts only for cards, not taken into account the rest of the system.
If you are working not giving to your cards the power they may need - your expencive "hard" is not used at 100%, they just will not work at full power (perhaps that is the reason that they are so cold "at full load" in your system with air cooling)... It may be that your PSU just can't give more than 450W (despite that is noted in its specs), and the cards just lower its load when they are getting not enough power from PSU...
And about another (my) system with four 580s - I may give you an another LINK, and you may count too: (4 cards) * (364 Watts) = 1456 Watt, plus the rest of the system min. ~200 Watt, total about 1600 in full load...

I wrote "not enough" about the "best case" - when you assemble the system giving to all cards (and to the rest of the system too) the ability to eat the maximum power that each card may even need in full load... In the case of 560s it is 358 Watt to each card. That will be the good system with enough power to "max load" cases... But you may install even 650W PSU, and it will even work (GTX are smart enough about power consumption)... but it will be not so good system... IMHO.

[johnb4467]

I wouldn't expect for you to get any performance increase with 2 x 470s replacing 1 x 560. In fact you may even get a decrease in performance. I have 2 x 560s but not the 448 models and I have a 460 card. The 460 card contributes maybe 20% to the total rendering power.

Are you sure? That does not seem to coincide with the charts in this thread:
http://www.refractivesoftware.com/forum ... f=9&t=7383

[johnb4467]

Code: Select all

johnb4467
With more than 2 cards you will not get normal temps with any air cooler system. I tried it already, don't waste your time.
I wrote already about it HERE after I ended up with config that I have described HERE.
And 1200 PSU IMHO may be not enough for 4 cards config...

Hi, and thank you for the response.
I would only be running three cards with a significant power draw, as I could not fit anymore in there anyway.
Some cards seem to take up more space than others, even if they are two slot designs. For instance, I have a GT 240 card that's passively cooled, and is two slot… But leaves enough breathing room for the 560-448. However, one 560-448 next to the other does not yield that same space. I am thinking that a 470 with a stock cooler (that outputs the majority of the hot air through the back of the card) might possibly yield enough room for the 560-448 to breathe…and with the 470 in the middle, leave the other side open for the other 560-448. Or at least that is my thought.
Seem even somewhat plausible? The cards might be hotter than normal, but my thought is that as long as they're not overly above normal, then they'd be fine?

[Leonardo]

It may be that your PSU just can't give more than 450W (despite that is noted in its specs), and the cards just lower its load when they are getting not enough power from PSU...

That is very interesting. My system draws 330W (measured from the wall socket) when I use octane and both gtx 460's kick in. I have an i7 2600K (not overclocked) with integrated graphics on a Z68 mobo. The PSU is a corsair HX650 which should work fine. The watts don't add up, do they? As a side note, the temperatures of the GPUs are 85 and 75. I have good cooling. Idle consumption is around 100W.
I know 650W is a bit weak for a dual card system, but I always assumed that I had headroom, based on the power readings. Actually, I was going to get bigger cards.

Are there any tests I could do before blaming the PSU? Are there any other causes for this (apparent) bottleneck? My megasamples/second are a bit lower than the thoretical values on t_3's wonderful benchmark table (my setup should give 3.50 Ms/s but I only get 3.12). Is it possible that the cards are 'locked' in some way? FYI they're both ASUS directCU, with a slight factory overclock.