Turn off SLI...
On Sun, Nov 23, 2014 at 4:22 PM, Parker de Waal <Parker.deWaal.vai.org>
wrote:
> Hi Scott,
>
> After putting together the machine and running the benchmark suite I've
> noticed that my performance is significantly worse than your numbers.
> Specifically, while running 2x cards in SLI mode the FactorIX-NVE I'm only
> getting:
>
> | Average timings for last 1000 steps:
> | Elapsed(s) = 5.19 Per Step(ms) = 5.19
> | ns/day = 33.28 seconds/ns = 2596.11
>
> Interestingly I get the almost the same number when running with a single
> gpu.
>
> I'm wondering if I set this up correctly as I've never built an SLI
> machine before. However, I have noticed that having SLI on ($
> nvidia-xconfig --sli=on) disables gpup2p (according the gpup2p checker).
>
> Are there settings you are supposed to specify to get that kind of
> performance?
>
> Best,
> Parker
> ________________________________________
> From: Scott Le Grand [varelse2005.gmail.com]
> Sent: Monday, November 17, 2014 5:42 PM
> To: AMBER Mailing List
> Subject: Re: [AMBER] 4x GTX 980
>
> GTX 980 is well on its way to provide blowout AMBER numbers despite the
> claims of its hopeful competitors (Really, will they ever learn? Nah...)...
>
> It didn't do so out the door because the performance a of key HW
> instruction was crippled relative to Kepler (llrintf).
>
> In the near-term future, either NVIDIA will address the above or we will
> adopt a workaround to stabilize SPXP and make it the preferred operational
> mode for GTX9xx cards. In fact, if you're using a thermostat, I *think*
> you can run JAC NVE in SPXP today at ~185 ns/day out of the box. This is
> of course the *correct* mode for directly comparing performance of unstable
> crappy MD code, but at least our crappy unstable mode is deterministic.
>
> Scott
>
>
>
>
>
> On Sun, Nov 16, 2014 at 8:16 PM, James Maier <jimbo.maier.gmail.com>
> wrote:
>
> > **Please note that all experiences I've cited are for GTX 780s.
> >
> > On Sun, Nov 16, 2014 at 11:13 PM, James Maier <jimbo.maier.gmail.com>
> > wrote:
> >
> > > Hi Parker,
> > >
> > > For the case, you can't go wrong with a HAF or almost anything with a
> fan
> > > on the side. We went with the "Thermaltake Overseer" for our cluster;
> > it's
> > > a bit cheaper than the HAF and has a built-in SATA dock. It's a pretty
> > neat
> > > case.
> > > Not that it matters, but the blue lights look exquisite against the
> green
> > > GTX logo.
> > >
> > >
> http://scanmail.trustwave.com/?c=129&d=jvrq1G8mSq5JFVaMS-53aR6yoV3GwD4haWghp9jzIA&u=http%3a%2f%2fwww%2enewegg%2ecom%2fProduct%2fProduct%2easpx%3fItem%3dN82E16811133194
> > >
> > > We actually moved the fan that's pre-installed on the front to the
> side,
> > > and put this "bgears b-Blaster" fan in the front instead:
> > >
> > >
> http://scanmail.trustwave.com/?c=129&d=jvrq1G8mSq5JFVaMS-53aR6yoV3GwD4haWwko9r_IA&u=http%3a%2f%2fwww%2enewegg%2ecom%2fProduct%2fProduct%2easpx%3fitem%3dN82E16835132022
> > >
> > > 120 mm, 103 CFM, not too expensive. We've not had any problems with
> them
> > > so far after about 9 months.
> > >
> > > As for the GPU, we've found the reference blower design to be more
> > > effective when trying to squeeze four GPUs right next to each other. I
> > > believe the blower style can generate higher (negative) pressure or
> > > something, because the ACX, while great on its own, seems to do a
> > terrible
> > > job when something's directly occluding it. Our ACX GPUs were also
> higher
> > > clocked though, so that's an important caveat to anything I wish I
> could
> > > tell you more definitively.
> > >
> > > But don't take my word for it; consult some BitCoin mining
> forums---they
> > > seem to know all about this stuff. I believe a forum like that is
> where I
> > > first read something about the reference style being better for >2
> GPUs,
> > > which seems to match our experience.
> > >
> > > As Scott has cautioned, "superclocked is a 'super' way to get
> inaccurate
> > > results." Sticking with a normal clockspeed will likely save headaches,
> > > esp. as the 980s are a new design.
> > >
> > > The other concern is power; you need a power supply with a rail with
> > > enough wattage for all cards or with separate rails that all can drive
> a
> > > card. I'm not sure if there is a single PSU that can "technically" (on
> > > paper, following all stats to the letter) drive four GTX780s (require
> 42
> > > Amps each, I've only been able to find +12v with 133.3 Amps, plus about
> > 5 V
> > > through each PCI slot). If someone knows of an adequate PSU, please
> > correct
> > > me.
> > >
> > > In that regard, the GTX 980s look promising due to their lower power
> > draw.
> > > There are only 2 issues I can think of atm:
> > >
> > > (1) 980s are "provisionally" supported by AMBER. This may not be an
> > issue,
> > > and according to
> http://scanmail.trustwave.com/?c=129&d=j_rq1PpOS9l3jkIDZU511Jlwn3ZzLHURsH2mJkZJLg&u=http%3a%2f%2fambermd%2eorg%2fgpus
> there's an optimization coming.
> > > (2) 980s are immature and thus the silicon is not likely as stable as,
> > > say, a 780 or a Titan.
> > >
> > > I'm guessing Ross, Scott, or anyone who has gotten their hands on some
> > > 980s can chime in more about the above points.
> > >
> > > HTH,
> > >
> > > James
> > >
> > > On Sun, Nov 16, 2014 at 9:28 PM, Parker de Waal <Parker.deWaal.vai.org
> >
> > > wrote:
> > >
> > >> Hi Everyone,
> > >>
> > >> I apologize for the off topic post, however I'm currently building a
> 4x
> > >> GTX 980 machine and was wondering if anyone had experience or insight
> on
> > >> picking a proper case/fans. I'm worried that 4 cards will lead to
> > >> overheating in most traditional cases.
> > >>
> > >> Additionally I'm wondering about the different fans on the GTX 980
> > cards,
> > >> specifically the reference fan blower vs. the ACX 2.0 fans on the EVGA
> > >> cards.
> > >>
> > >> Any insight would be extremely valuable.
> > >>
> > >> Best,
> > >> Parker
> > >> _______________________________________________
> > >> AMBER mailing list
> > >> AMBER.ambermd.org
> > >>
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> > >>
> > >
> > >
> > _______________________________________________
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> >
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Received on Sun Nov 23 2014 - 17:00:01 PST
