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Running Crossfire/SLI in x16/x4 mode?
- Thread starter hdpcgamer
- Start date
It'll be a bit more like 10-15% as I'm running 2 4870's here in x16/x4 and regularly see the x4 card hitting 99% usage in afterburner, but the x16 card is sitting somewhere around 70-85%.
This is with an i5 760@4ghz and at 1680x1050. If it was at a higher res I expect there would be an even bigger performance hit.
Plus it will also depend on how well crossfire is supported in the game that's being played, and I imagine the 5xxx series has slightly better scaling than the 4xxx cards.
I'll let you know
I can play it maxed at the moment (with no AA), but it does get very laggy in places.
I'm looking forward to it.
Btw, what FPS are you currently getting from Crysis with your single GTX 460 maxed out and is it OC'd?
Hmm, thats quite a huge performance hit.
Looks like my next motherboard will have to have x8/x8 then.
My 460 was OC'd to 820/1900. Don't know the FPS as I've never actually measured it. I'd count it as just about playable though.
The other 460 arrived today
the first thing is I'm amazed how much hotter two cards run than one. I've had to remove the overclock, and my soundcard to keep the temperatures below 90 (never topped 75 with a single card).Had time for a quick run of Heaven, and a bit of Crysis Warhead after wrestling with driver problems for most of the evening. Ran Heaven at 1080p and default settings and got an average of 59fps on the first run, with a minimum of 29 and max of well over 100
Warhead ran perfectly at max settings with 4x AA, but I haven't benched it or run fraps yet.Should have time to do more later in the week (as long as the whole thing hasn't melted by then)
This is correct from what I have tested.
I tried my 6970 with a friends 6970 on his 1156 motherboard (x16 + x4) and the performance hit is definitely noticeable.
Heaven bench marks for x16 + x16 & x8 + x8 are usually around 2400+(based on the benchmarks I have seen done on most popular sites, including these forums too), where as x16 + x4 was around 2000 (for my own test on friends pc).
I think there is a greater difference in performance with regards to the lanes in this particular circumstance because the two cards required at least x8 speed bandwidth each to perform well.
I think this is probably why x8 + x8 performs similarly to full x16 + x16.
Perhaps it would be less noticeable for slower cards?
I also read from another forum something similar to what is being discussed here.
http://hardforum.com/showthread.php?t=1473990.
Hope this helps!
My 460 was OC'd to 820/1900. Don't know the FPS as I've never actually measured it. I'd count it as just about playable though.
The other 460 arrived today
Had time for a quick run of Heaven, and a bit of Crysis Warhead after wrestling with driver problems for most of the evening. Ran Heaven at 1080p and default settings and got an average of 59fps on the first run, with a minimum of 29 and max of well over 100
Should have time to do more later in the week (as long as the whole thing hasn't melted by then)
I can't believe you are hitting over 90 degrees wiith both cards in SLI.
What exact cards do you have as I remember reading that 460s with reference coolers tend to be among the best in terms of noise and temps?
Also what case are you using?
To be honest, I haven't really given a great deal of thought on how the temps might be affected when going Crossfire/SLI. Ok yes, you would assume the cards would run hotter but at over 90 degrees? I'm also guessing that the noise from the GPU fans has increased due running at higher RPMs to kept the cards from melting?
Thanks for the quick benchmark of Heaven and quick play of Crysis and look forward to any other ones you have lined up.
Hmm, yet another forum confirming a big performance drop running dual-GPUs in x16/x4.
When you said that you tried your 6970 with a friends 6970 on his 1156 motherboard (x16 + x4) and the performance hit was definitely noticeable,
were you talking about the noticable performance drop from just benchmarking or from actual games, as looking at the GTX 480 SLI x4/x4 benchmark from http://www.hardocp.com/article/2010/08/25/gtx_480_sli_pcie_bandwidth_perf_x16x16_vs_x4x4 where the only game with a noticable drop in performance was Aliens vs. Predator - the minimum FPS dropped from 41 to 32. Every other game was pretty much on par.
Thanks for the link and an interesting read.
FWIW, I've looked at the consequences of going Crossfire on my P8P67 which would be x8/x4, and the general consensus is that there is very little in it between even 4x/4x and x16/x16 on PCIE2, where actual testing has been performed (single GPU cards).
I can't believe you are hitting over 90 degrees wiith both cards in SLI.
What exact cards do you have as I remember reading that 460s with reference coolers tend to be among the best in terms of noise and temps?
Also what case are you using?
I've got Palit sonic cards, and a CM Elite 330 case. The cas only has room for two 120mm fans, one intake and one exhaust. Yes it is much noisier now. My wife has already complained! The motherboard is an MSI P55-GD80 so there is an extra space between the cards to help cooling.
TBH I'm quite disappointed so far
The performance seems epic, but I'm not sure if it's worth it from a noise and heat point of view. Any suggestions to lower either gratefully received. I downloaded the latest bios for the cards to see if that helps at all. I guess I probably need a chassis with better airflow, but I thought I'd finished spending money on it fi a bit.
I was equally disappointed when i tried two 5870s in a CM690 with 8 fans (intake and exhaust) with a slot's space between the cards! The room got noticeably warmer especially around my legs where I sat next to the box and the noise was ridiculous. TBH it put me off going crossfire/sli again for some time I think and certainly not without after market cooling. I can see the benefits of the heat at this time of year but come spring it would be way too hot (heck it was too hot for it in september!).
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Ok, so I've bodged a 75mm fan into the side panel of the case blowing directly onto the graphics cards. I've also taken out all the spare PCI blanking plates. It's now not going above 78 on the top card so I'm much happier. It's lots quieter too. Progress
Sorry I should have mentioned it was from using 2 benchmarking tools (Heaven 2.1 & AvP) and not from actual game play.
That is a good point though, I don't think there would be too much difference in actual game play since a single 6970 (including cards in that range) is a good performer in most demanding games already. Although it would seriously annoy me knowing I should be getting 5-15% more performance out of two high end cards that scale really well in crossfire.
I compared my results to those that are already posted on the web, for example this thread: http://forums.overclockers.co.uk/showthread.php?t=18217424&highlight=6970crossfire.
Other reviews show very similar results.
I noticed while running the tests that one card(PCIe x4 slot) was at 99% activity all the time and the other(PCIe x16) was between 60-80% activity.
Im not really sure what that means if i'm honest :\
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In a system I built a while ago I accidently put the GPU in the wrong slot (a 4x) and the performance was rubbish.
Ok, so I've bodged a 75mm fan into the side panel of the case blowing directly onto the graphics cards. I've also taken out all the spare PCI blanking plates. It's now not going above 78 on the top card so I'm much happier. It's lots quieter too. Progress
I was just checking out your case and it seems to have decent airflow so why you were hitting over 90 degree completely baffles me lol.
I'm glad you managed to sort out the problem with the airflow of the case and dropping down to 78 degrees is a massive difference.
Would you say that it was the 75mm fan or removing the PCI plates that made the biggest difference?
Not quite sure what's made the difference.
They're for sale now anyway! I've got the temperatures under control, but the noise is still a bit of a problem. I suspect my PSU isn't quite up to the job, as that's getting very hot and noisy as well, and I can't really afford to upgrade that at the moment. SLI hasn't turned out to be all I'd hoped If I can move the cards on, I'll get one of the GTX 480's that are on offer at the moment and see how that goes.
They're for sale now anyway! I've got the temperatures under control, but the noise is still a bit of a problem. I suspect my PSU isn't quite up to the job, as that's getting very hot and noisy as well, and I can't really afford to upgrade that at the moment. SLI hasn't turned out to be all I'd hoped
If I can move the cards on, I'll get one of the GTX 480's that are on offer at the moment and see how that goes.Not quite sure what's made the difference.
They're for sale now anyway! I've got the temperatures under control, but the noise is still a bit of a problem. I suspect my PSU isn't quite up to the job, as that's getting very hot and noisy as well, and I can't really afford to upgrade that at the moment. SLI hasn't turned out to be all I'd hoped
I was going to mention that you may be stressing your 600w PSU a bit running 460s in SLI.
Are you sure the additional fan noise is coming from the 460s and not also the PSU?
You could also check to see which 460 is creating the most noise and perhaps replace that instead of getting rid of them.
You are aware that you would be going backwards performance if you go for the 480?
A lot of the fan noise is the PSU, it's also creating lots of heat which is really not helping. The hot air coming from it was raising my CPU temperature by almost 10 degrees. I guess you learn to check your power requirements before you buy the hard way.
I basically have two options. Buy a decent 750W plus PSU, or sell both cards and get hold of a better single card with the money. I'd like to get the PSU but I suspect that's an expensive option.
I know two 460's beat one 480, which is why I wanted that setup in the first place.
I basically have two options. Buy a decent 750W plus PSU, or sell both cards and get hold of a better single card with the money. I'd like to get the PSU but I suspect that's an expensive option.
I know two 460's beat one 480, which is why I wanted that setup in the first place.
I take it you never thought about going SLI when you brought your PSU?
Theres a also a chance that a 480 running in your current system would carry on stressing your PSU thus the noise will remain the same. Plus aren't the 480 known to be very power hungry and noisy?
According to the Nvidia website 600W is ok for the 480, whereas the approved PSU's for 460 SLI all seem to be 700W plus.
When I bought the power supply I was running a HD4770, and had no idea how hard the upgrade bug would strike. The only part of my rig that remains from when I bought a pre-built system 15 months ago is one of the hard drives!
When I bought the power supply I was running a HD4770, and had no idea how hard the upgrade bug would strike. The only part of my rig that remains from when I bought a pre-built system 15 months ago is one of the hard drives!