Re: Three GPU cards on shared-mem motherboard

From: Aron Broom (broomsday_at_gmail.com)
Date: Wed May 30 2012 - 22:03:24 CDT

Ahh, so if bandwidth wasn't a bottleneck one could get quite a lot out of
those.

On Wed, May 30, 2012 at 9:02 PM, Axel Kohlmeyer <akohlmey_at_gmail.com> wrote:

> On Wed, May 30, 2012 at 8:50 PM, Aron Broom <broomsday_at_gmail.com> wrote:
> > I'm not aware of any motherboards that have 3 PCI-E 3.0 slots yet, there
> > appear to be some with 2. I haven't looked very hard, I imagine in a
> year
> > or so it will be more common.
> >
> > To reiterate something someone else mentioned, I believe the 690, much
> like
> > the 590, is just two 680 cards together. It also, therefore, needs two
> > PCI-E slots for the one card. In the case of the 500 series cards, I
> found
>
> this is incorrect. both the GTX 690 and the GTX 590
> (as well as the GTX 290) only need a single PCI-e slot
> (double though). the two GPUs are placed behind a
> PCI-e bridge and thus have to share the available
> bandwidth when used both. so this sense they are
> similar to (server) mainboards that offer a lot (i've seen
> them with up to 8) of "full" 16-lane PCIe slots.
>
> axel.
>
> > the 570 performed at about 85% of the 580 on a 6-cpu-core system with a
> > 100k atom system being simulated in NAMD, but the price was ~66%. I'm
> not
> > sure if this will be true for the 670.
> >
> > As a final note, there has been some attention on the fact that the
> latency
> > (which particular latency I'm not sure) on the 600 series is higher, but
> > that for games that is more than counterbalanced by the additional cores.
> > It's not clear to me that this would be the case necessarily for MD, so I
> > would really urge trying to find some avid gamer with a 670 or 680 and
> > getting them to do a quick benchmark before investing in those cards.
> >
> > ~Aron
> >
> > On Wed, May 30, 2012 at 1:33 PM, Francesco Pietra <chiendarret_at_gmail.com
> >wrote:
> >
> >> Forgot the list previously. Sorry
> >> f.
> >>
> >> ---------- Forwarded message ----------
> >> From: Francesco Pietra <chiendarret_at_gmail.com>
> >> Date: Wed, May 30, 2012 at 7:28 PM
> >> Subject: Re: namd-l: Three GPU cards on shared-mem motherboard
> >> To: Vincent Leroux <vincent.leroux_at_loria.fr>
> >>
> >>
> >> On Wed, May 30, 2012 at 6:14 PM, Vincent Leroux <
> vincent.leroux_at_loria.fr>
> >> wrote:
> >> > Hi,
> >> >
> >> > A GTX690 basically is two GTX680 chips on a single board. No surprise,
> >> this
> >> > is twice as expensive. You may have a hard time finding one on the
> >> market.
> >> > In addition, I am not sure you can put more than two on a single
> >> > motherboard, this may be technically impossible. And if you have two
> you
> >> > have to make sure the motherboard design leaves enough space between
> the
> >> two
> >> > cards, if they are too close the top one will probably die very
> quickly
>
>
>
> --
> Dr. Axel Kohlmeyer
> akohlmey_at_gmail.com http://goo.gl/1wk0
>
> College of Science and Technology
> Temple University, Philadelphia PA, USA.
>

-- 
Aron Broom M.Sc
PhD Student
Department of Chemistry
University of Waterloo

This archive was generated by hypermail 2.1.6 : Tue Dec 31 2013 - 23:22:02 CST