SLI in a nutshell is a way of using more than one graphics card at a time for a
richer gaming experience with higher frame rates and more in-game eye candy
turned on you can learn more about it in this video here on Techquickie now
NVIDIA's website is full of certain
information about SLI technology which graphics cards support it where to buy
the other Hardware you need guides on how to set it up but I noticed that
Beyond one specific 2-way SLI
configuration at one specific resolution they don't seem to even want to talk
about the value proposition of adding in
more cards or how performance scales in
relation to the cost as you put more and more graphics cards in your gaming PC so
when a unique opportunity fell into my lap to test two-way three-way and
four-way SLI with the brand spanking new gtx980 at 4K I jumped on it
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click now to learn more I'm going to jump right into numbers here because
they actually only tell part of the story I tested four games with details
cranked at 4K resolution on a Gigabyte x99 gaming 5 with a core I 749 30k 6
core at 4 GHz and 16 gigs of 24 100 MHz
ddr4 memory and then I threw a Corsair ax 1500i power supply on the bench
because I was concerned about power consumption and overwhelming the
existing one but more on that later so
let's start with what should be the poster child for multi-way SLI Tomb
Raider 2013 if all you do is hang around and play Tomb Raider go buy 4 GTX 980s
hell buy an extra one to keep on your desk to remind you of how great it is
you get 30 FPS average with one card then 20 3 to 24 more frames per second
with each additional card almost the same scaling going from 1 to two 2 to 3
and 3 to four cards and on top of that the animations are butter smooth with no
perceptible micro stutter outstanding
it's just too bad not every game is like this if Tomb Raider is the poster child
Watch Dogs is the one in the corner with the duns hat scaling from one GPU to two
seems okay at first glance if we only look at average frame rates but minimum
frame rates tell a bit more of the story they dropped almost in half and this
hitching and stuttering was very noticeable in game it actually gets
worse the more graphics cards you add yet another issue for the PC version of
Watchdog next up is Far Cry 3 something
unusual you might notice about this game is that the minimum frame rates are very
close to the average frame rates in some cases this is because our run for this
game involves driving around a track running over dudes and getting shot at
and looks very consistent having minimum and average frame rates close to each
other makes animations appear very smooth on screen at least with one or
two gpus installed in the system even though average frame rates scale very
well with more gpus you can see that minimums don't and this manifests as
uneven inconsistent movement of objects on screen with three or four graphics
cards our last game is Crisis 3 just
like Far Cry 3 it scaled well from 1 to 2 gpus but we see the same issue with
great average frame rate scaling and poor minimum frame rate scaling that
translates to uneven lurchy animations in the case of Crisis 3 it was actually
noticeably worse than Far Cry 3 with three-way and four-way SL so much so
that as a gamer I would much rather play with two graphics cards at lower detail
settings than with more graphics cards and game settings cranked speaking of
in-game settings if you want to see how I was running everything check out the
download link in the video description GPU boost clock speed was another
interesting part of the story with two gpus we saw slightly lower turbo speeds
because we hit our thermal limit sooner on the top card than the bottom one
because it has less access to Fresh Air surprisingly though we reached the same
GPU speed even in the other configurations pretty impressive when
they're all packed in like sardines in a four-way config speaking of impressive
power consumption I mean I mentioned before I threw A500 watt 80 plus
titanium PSU in this rig to ensure that
I wouldn't be limited the fan on it barely even turned on our four-way SLI
configuration Drew 620 Watts from the wall in our stare at the fire test in
Far Cry 3 that means that even accounting for another 50% capacity for
future expansion 1,000 watt power supply would have been plenty for this rig so
it's back on the bench all right now back up a second line is you run in here
throw a bunch of graphs in our faces for five minutes and then basically voice
over telling us to ignore the performance numbers because they don't reflect the gameplay experience what
gives great question normally when we do
benchmarks on this channel it's okay to use fraps to take average frame rates
and compare graphics cards relative performance because in our game
showdowns and our graphics card reviews we only test single GPU configurations
with multi-GPU configurations particularly Beyond 2-way as I've been
discussing in this video different measurements need to be taken
to evaluate the evenness of the pace
with which new frames are delivered to the gamer here's an example the video
you're watching right now is playing at 30 frames per second
smooth hold on a second what was that we only dropped the frame rate 3% to 29
frames per second but because we're doing this by dramatically increasing
the delivery time of just a few frames periodically you're seeing very
noticeable hitches and stutters aren't you that's what I'm talking about now
unfortunately we don't have the equipment to objectively measure the
perceived smoothness of a game like you'll see on some of the hardcore Tech
sites like PC per and tech report I recommend reading up on those sites by
the way uh search for frame pacing if you want to learn more about this but
the good news is that in the case of our multi-way SLI video today at least with
this new and relatively immature driver for the GTX 980 it was easy to pick up
on this stuff with the naked eye so being able to measure it wouldn't have
changed the conclusion much and here it is what we've been saying for years is
still true one of the fastest GPU you
can afford is best in most cases because you'll always get the performance you
paid for even in Watchdogs until you get
up to the top tier cards at which point two of them might make sense if you
really are hungry for more performance but beyond that things really come off
the rails in a hurry and I guess I can see why NVIDIA offers you the capability
to run more cards if they want to but didn't even have any three-way or
four-way configs running even in their own demo systems at the gtx980 launch
event so that pretty much wraps it up guys like this video if you liked it
dislike it if you disliked it leave a comment letting me know if your feelings are more complicated than this check the
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