GTX1080Ti 2-way SLI, if open cooler model - it is 3 lane FAT !!!

HI Gang,

So that you guys do not get same problem as I am having, here goes...........

I started into sim only a few weeks ago. Only having pedal and steering like less than a week.
I spend more time benching DX9 vs DX11, since I do not have steering and pedal weeks ago... LOL.
Its all AI driven.

Anyway, I started with oldie GTX980 x 2-way SLI.
Top is open cooler type with 2 fans. Occupy PCIe slot 1 and 2.
PCIe slot 3, empty
Bottom one is founder edition type with regular single blower type fan. Occupy PCIe slot 4 & 5
PCIE slot 6 for PCIE-SSD using M.2 memory

.

Since it is driving 2560x1440 triple monitors, FPS been bad/slow if at best resolution.

So I bought GTX1080Ti, 2 units. Open cooler ones. This open cooler model is FAT !!!! as in per unit is 3 lane, so two units = all 6 PCIe lane gone !!

The mobo above is X-99 Asus Deluxe gen 1, year 2014.
It has two DIMM channel B1 and B2 not recognizing the DRAM....damn. Bad luck #1
So me need new mobo because GTX1080Ti x 2 is powerful and I do not want memory problem from this handicap now-no-more quad channel mobo.

I actually wanted to get mobo with 7 PCIE lane, so that I can use my PCIE-SSD while able to do 2 way SLI . There was one Asus X-99 workstation model with 7 PCIE lane, like 2 years ago the model and not selling well .So no one stock it now in my country...damn. Bad luck #2
https://www.asus.com/Motherboards/X99E_WS/

So I am stuck with 6 PCIE lane mobo.
My Asus X-99 deluxe can use M.2 SSD, where my PCIE SSD is actually an M.2 with PCIE adapter, BUT because the Noctua cooler block the location of X-99 Deluxe M.2 slot and hence PCIE adapter it must use. This mobo M.2 install is right up like rocket for take off...LOL.


Desperate, I ended up with Asus X-99 STRIX mobo. At least the M.2 SSD will be installed sleeping style, but under the 2nd GPU. So save money on M.2 which is still useable, while getting new mobo to avoid defective quad channel memory of old mobo....but GTX1080Ti x 2 will be VERY CLOSE, with little air gap.

.


Probably even a fly have problem entering the gap between the GPU-s


I tested the top GPU solo, no 2nd GPU, using Heaven ( GPU test ) at ULTRA. 55 celcius. nice
I then tested again with Heaven , with 2 GPU installed just to check how bad air restriction will heat up GPU #1 the top one, not in SLI mode, just top GPU running = 71 Celcius... damn Bad Luck #3

65C is the max I will allow my GPU to run continuos, regardless Nvidia stated typical 80C as max.
Any electronics, cooler the better.

At least my M.2 SSD has a new home now... . I removed the sticker.


But it is not as cool as my regular cased Samsung 840 Evo SSD at 35C casing temperature.
My room ambient temp is 27-28C.

This M.2 is 53 Celcius before GPU #2 blocking it ...no good.


.
Can be cooler...but crude


Then come another BAD LUCK...which actually occurred much earlier but I did not really care.
My Leo Bodnar steering controller, when its USB is connected to my PC, be it X-99 Asus Deluxe or X-99 Asus Strix gaming mobo, will not allow my PC to boot. It will get stuck at Window Starting screen... that Window Logo thingy. I can connect PC to Leo controller box, but only when PC already booted up and Window7 running. This is why I said, I did not really care at first....but now I care

So I contacted Leo tech staff and they told me that X99 from Asus has a bug... wow !!
Bad Luck #4 it is then. They will send me a PCIE USB adapter, this model : https://www.scan.co.uk/products/2-port-scanfx-hpu-300nc-v2-superspeed-usb30-(nec)-5gbps-pci-express-card
Oh oh..I am in deep shiet...because when I do SLI, there is no space left for other PCIE based add-on.
All un-used PCIe slots will be blocked by the two FAT GPU-s !!

Indeed Leo engineer is kinda correct to say about the bug.
The Asus X99 Strix gaming mobo has 3 USB chips. 1 of Intel and 2 of ASMEDIA 3.0 and 3.1 ( USB-C )
On Asus X99 Deluxe mobo, as long as PC already running Windows7, any USB port if I recall correctly will work when Leo controller is then connected to PC. I never tested all USB ports, too many. It has 20 including the front panel ones.

This X99 STRIX is weird. One of the Asmedia USB chip 100% does not like Leo controller box. I am always getting USB DEVICE NOT RECOGNIZED even after PC already running. The other 2 USB chip its okey..when PC already running.

So what will be my solution to my 2 problems ?
01. Too hot GPU#1, the top one
02. No space for PCIe-USB adapter, to make Leo controller work with Windows booting process, without trouble of un-plugging its USB cable.

I have ordered this, but it will take time to arrive from USA.
https://www.digikey.com/products/en?mpart=8KC3-0726-0250&v=19
PCIe extender cable, by 3M.

I dare not buy unknown brand, when I read even Thermaltake ones are crap. They supply such cable for their special Wall Mounted Core P3 and P5 chassis. Dang, I did not know they wall mount PC-s...he he he. NOTE : Me is IT un-knowledgeable.
http://community.thermaltake.com/index.php?/topic/43213-attn-users-with-thermaltake-riser-cables/

I cant take risk with my 2 of GTX1080Ti, 8 core i7 5960x and X99 mobo if a PCIe extender wire will blow my PC

I think the PCIe extension cable will work. I dont believe 3M dare to sell junk.


This is how the 3M cable looks like in real use..... 50cm version


For techie guys, this is 3M cable test video for the Twin Axial Cable.
So the PCIE extension is Twin Axial cable type of TwinMax


Will report progress in 45 days....

 

I suggest for PCIe 6 lane mobo needing GXT108Ti 2-way SLI, get 1 open cooler and one founder's edition single blower version.
https://www.kitguru.net/components/...-rog-strix-gtx-1080-ti-oc-o11g-11gb-review/2/
I think founder's edition GTX1080Ti maximum is 2.5 pcie lane fat or maybe like my GTX980, 2 lane fat only.

 

challenge: start, at back, full grid visible, Monaco, night, heavy rain, max AA, ultra pp, max settings, 5760x1080

 

Hi Louis & John,

Louis me so sad now
Rfactor 2 does not scale well, perhaps negative scaling in my case with GTX1080Ti... hick hick hick.
Was not like this when it was GTX980 x 2, but I can't test 7680x1440 resolution with a single GTX980.
I did get a bit of SLI scaling with 2560 single monitor.

I did a quick n dirty test, itchy hand....as usual
Attached the sad truth.... in PDF.
NOTE :
1. Me IT dummy, so I may not maximize some parameters (whatever they are ) compared to someone with great IT skill.
2. I do not yet have the HighBandwith SLI bridge yet. I read it matters a bit at 4K resolution or higher, which means my triple 2560 monitors will need it.
3. Maybe soon Nvidia newer driver may help. I am still on 382.05
4. I do not OC my CPU, I let Asus BIOS do Optimization at I think 3.8 Ghz.
For memory I let Intel XMP do auto tuning. I am on 2666Mhz DIMM.

I only see GPU load, if it is 95% to 99% on both GPU-s, I assume the SLI works well.

Poor SLI scaling is not un-common...but mine its like negative scaling ...LOL. Must be bottleneck somewhere. But Heaven GPU test showed good SLI scaling... hhmmm...headache...headache.
http://www.babeltechreviews.com/gtx-1080-ti-sli-performance-25-games/3/


John,
I am scared of water cooling. If a leak occurs...me in trouble.
Also messing around with the PC removing this and that internally, its more complex if water cooled.

Thanks for the advice/idea BTW...much appreciated.

 

rFactor 2 is broken out off Nvidia Inspector's bit editor which means that SLI does not work as it should. However if you are using Nvidia default bit 0x02402004 - Single GPU you are able to force equal GPU load in both of your cards.

Nvidia cards are able to handle max temps up to 90 c and temps like 70 c are not dangerous but of course with high temps you GPU don`t perform as well as with low temps which you can easy see if you are looking how Nvidia GPU boost is boosting up your GPU with different temperatures.
To get optimum performance out of you SLI there is few things you must remember.
You must be sure that SLI is running PCI-e @3.0 x16x16.
Don`t use audio card, PCIE-SSD etc. in PCI-e slots it might limit you SLI performance with some MBO`s or downgrade PCI-e @3.0 x16x16 to PCI-e @3.0 x8x8.
Look that PC ram (mhz) is not limiting PC`s GFX performance. (To not bottleneck 1080Ti ram must be DDR4@3000 mhz or better)


My PC spes:
MBO: Asus X99 WS-E/10G,
CPU: i7-5960X@4.4Ghz,
RAM: 64 GB Ripjaws 4@3000 CL15,
GPU: 3 x MSI GeForce GTX 1080 Ti SEA HAWK EK X

 

Aha ... that X99 WS is the 7 pcie lane mobo I wanted.
Aha special liquid cool GTX1080Ti and 3 of them !!! ... awesome, no wonder you have space for 3 GPUs and good performance at such resolution... he he he.

* Check , SLI bits 0x02402004
* Check, 3.0 16x both lane. Did GPU-s load test already.
* No Pcie SSD stealing PCie lane. Its M.2, Asus X99 STRIX User Manual did not say it is sharing with any PCIE lane
- I only clock to 3.5Ghz my CPU Asus auto optimization and XMP at 2666mhz, I just checked a few minutes ago, not 3.8Ghz..... not 4.4Ghz like yours. Me dare not OC to that level.

What baffled me is, why 2 way SLI for my GTX1080Ti is slower than Single , more so in DX11 ?
Zero gain is okey, negative gain is so confusing
My GTX980 was not like this, SLI at 2560x1440 did gain some...but again I can't then test 7680x1440 resolution.

Anyway thanks a lot Ari.
Me will do more checking yah. Learning ...learning.

Have good weekend.

 

@suryaprihadi I can only see that you RAM mhz is bit low but it should not result to negative gain. I think it is DX11 and "(rFactor 2 is broken out off Nvidia Inspector's bit editor which means that SLI does not work as it should)". Look in to you BIOS that all is OK and try to run with lower in game settings and look if high frame rates gives you better gaming experience in rF2.
I have 3x1080Ti yes but running 3-way SLI is not easy and in most games it is mission impossible, I am using 2-way SLI mostly.

When we get final release of DX11 I look closer in to it and I am sure we can together figure out how we can get good SLI performance.

 

Hi Ari,

Thanks very much for looking into my SLI sorrow state
I agree, this SLI thingy is very complex, more so for triple screen.
I tried 0X08000F5 for DX11, I think I iRacing bits.
GPU dont load well if triple screen 2560, 50% ish for both and FPS jump like crazy.

I then use Assetto Corsa bench mark tool.
AS handle well SLI even in highest setting including PE maxed out, I can see the goodness of the 2nd GPU.

Lets hope S397 sort out SLI compatibility bits.
I really like RF2, its physics is much better than AS.

thanks

 

@suryaprihadi I am not sure if you know that fullscreen don`t work with DX11 as it is supposed to do. Fullscreen is random, sometimes you are in windowed mode and sometimes you are in Fullscreen. Windowed mode gives you unlimited fps and picture is out of the focus.If you hit alt+tab you get low fps in my case it is 30-40 fps. The best way to be sure that you are in fullscreen mode is to cap FPS in plyer.JASON or use video sync.
If game is not in fullscreen mode just restart and it is usually ok, if not restart again
Fullscreen bug can be the reason why you have low benchmark results in Rf2 and why negative gain with SLI

 

Hi Ari,

Okey me will learn more of fullscreen definition.
What I been testing so far is like this :

Fullscreen + multiview mode is where it is smoothest so far at this low FPS I am getting with SLI.
Smoothest is when the car from pit driving out to track at slow 46 FPS in Nords Tourist Autumn , where many corners are 90 degress., I am getting less frame skip or micro stutter. I can tell I am in fullscreen if my Afterburner small detachable DATA window like this one :

is no more able to overlay itself in RF2. In windowed and borderless mode , this small Afterburner DATA window will be able to overlay itself in/on the game. I do use Afterburner's Riva Server to do the real overlay of data on the game.

Since day 1 I only use fullscreen, because I thought multiview only work with fullscreen...LOL, what a dork me. I tested today and it is not the case.

In windowed and borderless mode, now with poor SLI - 46 FPS, pit to track, at 90 degrees turn, I can see more frame skip or micro stutter.

Its overall function between windowed, borderless and fullscreen, that is all I know ...LOL.

Now in DX11 the multiview adjustment does not work anymore, that "CRTL+="
I think in DX9 latest also its not working.
EDIT : When I remove the 2nd GPU, this feature now can appear !!
I think need to wait for proper SLI bits from S397.

The FPS is no different for me in windowed, borderless and fullscreen for first 60 seconds from pit to track, Nords Tourist Autumn start at 46FPS and then climb to 80-90 at that S bend with wall . Only when I turned off Multiview, then at pit it is 65FPS. I can get that , at less by 5FPS only with single GTX1080Ti same all best setting, no need SLI

Pressing Atl+Tab works in all 3 modes for me, DX11, but no FPS increase.

Thanks for thinking other ways of troubleshooting for my case, really nice of you.
I will do more testing.....

 

I find it strange that you have so bad performance, something must be horrible wrong.

This are settings I am using with DX11 which gives me capped 120 FPS res: 10320x1440 when I am using latest updated DX11 (S397) ISI content:

rFactor2 video settings:
Mode > Fullscreen
Anti Aliasing > 3
Post Effects > Low
Sync> Video

Inn Game > Options > Display:
Circuit Detail > High
Player Detail > Full
Opponent Detail > High
Texture Detail > High
Texture Filter > X16
Special Effects > Full
Shadows > Medium
Shadow Blur > Optimal
Soft particles > Off
Rain Drops > Yes
Road Reflection > Off
Environment Reflection > Low

 

Hi Ari,

Thanks for feedback.
Indeed I am in bad luck with RF2.
Other games can scale my SLI and so is Heaven GPU test.

I can do non capped, at average 135 FPS on the track or near ending of pit there after, 95-100% load ,single GPU only, exactly copying your setting. Silverstone GT track. 20 AI cars set, semi cloudy or rain. AI drive my car
Parked at pit garage is 85FPS, when stationary. Anti Aliasing at 5 doesn't drop much FPS too.

But remember mine is 3.8 mega pixel smaller than your surround set up and that is like 2 of 1080p extra monitors you are having on top of my 11 mega pixel surround set up.

Actually I would like capped 120 FPS, DX11 in Post Effect at MEDIUM and all other setting at MAX/BEST/FULL , that is what I hope 2 way SLI will bring.

I shall experiment more when my PCIE extension cable arrive and me can do proper cooling for GPU 1 when in SLI mode.

Seeing CTRL+= not showing when I am in SLI mode, I am sure something is wrong.
I read Nvidia SLI 101, it seems a great deal will depend on game developer.
So let see how S397 DX11 will progress.

Again thanks very much for your troubleshooting guide.

 

DX11 build 1915820 27 june 2017, more test.
Still ...2 way SLI has no effect ...

 

@suryaprihadi thx for testing.
Could you run one more test with no DX11 bits (0x00000000)?

 

I did Ari. It is in the zip. I call it DX11 bits : all zero but only for SLI

Forgot to add, if you are not looking at SUMMARY, which then are the actual original logging files, the yellow highlight marked the start and the stop of the logs of the pit to 1 round of track.

 

SLI has never worked well with rF2, I suggest you run rF2 with one card and save some electricity. ISI was asked to fix it for 3 or 4 years, they didn't. Now it may be that Studio 397 will look at it, but it may also be that the game engine is fundamentally not working well with SLI, in which case it may take very long to fix it. Many new games, even AAA titles, scale poorly or don't work with SLI at all.

 

Hi Stonec,

In DX9 and lower resolution like 2560 x 1440, the SLI does boost a bit, +-25% fps gain, when I was on GTX980 x 2.

I think S397 is working on DX11 SLI .. cross fingers

 

DX11 SLI GPU usage is 89-100% with bits 0x00000000 which is fine but there is no increase of fps SLI vs single card and decrease of FPS DX9 vs DX11 is 20%.

 

Yes Ari, that is why it is so confusing. 2 GPU-s pumping out workload 90% x 2 to 100% x 2, but not doing any better than 1 same GPU doing 100%. Its like these twin GPU doing identical work, instead of workload sharing as how an SLI should be doing.

I know some games do not scale with SLI and some get negative too... as you and Stonec put it...DX11 SLI is broken..., more so above 2560 x 1440p.
http://www.babeltechreviews.com/gtx-1080-ti-sli-performance-25-games/3/
Too bad these reviews to do state GPU loads in single vs SLI.

Need to be patient