P3Dv4.3 : my observations

[KL Oo 700]

Thanks Skywolf.

Is there a downside to SLI? Rob seems to have had some issues with it breaking each driver version - has this been your experience too?

When you say it goes bonkers if GPU usage goes above 90% I presume you mean FPS drop dramatically? I get the same behavior with my 1080 in heavy GPU environments, but from where I sit adding another card can only really increase the amount of data that can be pushed through the GPU(S) before you reach that level right?

 

[Skywolf 992]

10 minutes ago, KL Oo said:

Thanks Skywolf.

Is there a downside to SLI? Rob seems to have had some issues with it breaking each driver version - has this been your experience too?

When you say it goes bonkers if GPU usage goes above 90% I presume you mean FPS drop dramatically? I get the same behavior with my 1080 in heavy GPU environments, but from where I sit adding another card can only really increase the amount of data that can be pushed through the GPU(S) before you reach that level right?

 

FPS drops happen when SLI link between the GPUs goes out of sync.  That is when chances increase for P3D crash.  At times I have even seen, SLI is broken and entire sim is running on one card.  Usually moments later P3D does crash.

I tested with single 980 and my FPS are way less on 4K.  SLI is the only way I am able to enjoy P3D4.3 with complex addons and sceneries.  It is no magic bullet, but I get the performance boost.

Amount of data is still limited to pci express bus and what speed are your lanes.  With my i7-5820K - I get 28 PCi Express lanes that means I can do 8x/8x in SLI mode.  If I get the next level cpu in the family which has 40 pci lanes - then I could do 16x/16x.  Single use card does run in 16x.

For SLI throughput 16x/16x should help.  8x/8x is good but it is also P3Dv4 graphics engine.  At this stage it has tons of legacy code in it.  Till we get new complete engine - I am hoping for v5...then everything is new again.  Lets see.

Just don't saturate the card to its full limits.

I am having amazing time with 4.3.  Amazing release though

Edited July 28, 2018 by Skywolf

[KL Oo 700]

Thanks. I've never run SLI so am curious to try it... Might wait until the 1180 arrives and see how that performs first though.

[Skywolf 992]

6 minutes ago, KL Oo said:

Thanks. I've never run SLI so am curious to try it... Might wait until the 1180 arrives and see how that performs first though.

Yes...that is what I would do too first.

 

[GSalden 4,657]

6 hours ago, KL Oo said:

Hi Gerard,

I understanding from this thread you're not running the virtual cockpit?

I'm very impressed by your SLI results but am interested to see if you get a similar improvement when using the VC. Are you able to post any results using the VC in SLI mode as opposed to VC without SLI?

Cheers,

 

Here I have a Full suze 737-800 home cockpit which is running on Prosim - P3Dv4 . Therefore no VC.

I have a 737 TQ that is only working with that combo. Therefore I can only test like I do now.

But sure you will benefit too : beside the VC you will also see the outside world and there you will see your gains. 

I am not sure but probably the cockpit shadows will benefit too from SLI.

[GSalden 4,657]

6 hours ago, Skywolf said:

Yes...that is what I would do too first.

 

For myself I choose to buy a second 1080 Ti instead of waiting. 

A new 1180 /2080 will be faster but 30% faster in P3D is a lot. My experience is that it might be 10-15% max with each new , same type  of card ( 1080 —> 1180 )

The advantage with SLI is having to GPU’s working together ...

Surely an 1180/2080 SLI setup would be faster 🙃

[GSalden 4,657]

The question now is : how will P3D behave regarding losing FPS over time when flying over heavy scenery...

I have the feeling that that is still happening. Only now with more headroom I might lock FPS just slighly higher instead of 30% higher.

Also I am wondering If locked vs Unlimited has an influence.

Anyone of you experiencing the FPS drop has ever tested that ?

[Chris Bell 165]

i am not experiencing tissues but have tested frames locked vs unlocked,
since i run the test my frames remained unlocked!

old FSX tweak and tricks no longer apply in P3D,
if i lock my frames it somehow becomes worst than unlocked,

flying over the L.A. grid at night i will get around 19 frames with frames locked at 30,
with frames unlocked i am getting a much smother experience specifically over dense and harsh area vs locked,
the same test over the L.A. grid with unlocked frames yields a close to 30 frames,

1080Ti results, on the left with frames locked at 30, on the right Unlimited,
(credits: test results compliments of Mike @Cruachan)

 

 

Edited July 29, 2018 by Chris Bell

[GSalden 4,657]

If I am correct Unlimited means a FFTF of 0.01 and Locked 0.30

With FFTF Dynamic the FFTF value can be changes so Locked vs Unlimited will have the same value to test with..

[Chris Bell 165]

LOCKED 30 With FSPS FFTF Dynamic

[GSalden 4,657]

What FFTF value ?

[Chris Bell 165]

FSPS FFTF is Dynamic AFAIK 
these are not my own TI results; i believe no custom FFTF used in first pair presented,

3 hours ago, Chris Bell said:

(credits: test results compliments of Mike @Cruachan)

Edited July 29, 2018 by Chris Bell

[GSalden 4,657]

37 minutes ago, Chris Bell said:

FSPS FFTF is Dynamic AFAIK 
these are not my own TI results; i believe no custom FFTF used in first pair presented,

You can use fixed FFTF values too .

Eg : ground = 0.01  /  2500 ft = 0.30 

So flying at 2500 ft at 230 KIAS is 0.30. Using Unlimited and Locked can be tested this way..

[Guest]

Dynamic FFTF?

changing FFTF will lead to blurries.

unlimited is not FFTF = 0.01, that code is completely bypassed when unlimited that’s why Vsync lock is needed

Chris/Gerard, you gents have been around a long time and I know you know FFTF changes can result in blurries.

Cheers, Rob

 

[Chris Bell 165]

indeed Rob (bit surprised here too!),
i have not suggested any changes to FFTF,
i believe Gerard's inquiry is just for bench marking purposes?

Edited July 29, 2018 by Chris Bell