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Going SLI


Bandit

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Hi guys I am thinking of buying a second GTX275 card and running them SLI.

Question:

Do the cards have to be exactly the same model for SLI to work?

imho that would be the best approach, however fsX does not support SLI, in fact I've heard from various sources that when applying SLI the fps went south, so tread carefully

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Wolter is right.

I had two 9800 GX2's in quad SLI and thought I was doing great.

After a discussion on the forum, I took one out and found that my frame rates actually increased and the sim ran smoother.

9800 GX2's are an SLI card anyway (2 x GPU's bolted together) but I am now firmly convinced that running SLI for FSX is an utter waste of time and money.

My next buy will be a 300 series single GPU model with 2 GB Ram at least.

Frank

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Thanks Wolter. Anybody using SLI under FSX who can advise?

Here's what looks like an informed view. I have no personal experience with SLI but as I use a TH2GO and have very limited AA performance I am assuming I'm one of those who would benefit.
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Thanks Wolter. Anybody using SLI under FSX who can advise?

Here's what looks like an informed view. I have no personal experience with SLI but as I use a TH2GO and have very limited AA performance I am assuming I'm one of those who would benefit.

I assume by this, you mean I'm uninformed?

Frank

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I would have thought, and it is my view, that SLI is a feature of the graphic cards and driver and not the application because you can enable/disable SLI in the video driver and not the application/s as well there is an SLI performance mode setting in the driver. From looking at the settings on my SLI driver, I think the SLI can either make an improvement in performance or you make the image look better. I also prefer to let the graphics card to do the work, such as anisotropic filtering and AA etc. As the driver allows for enable/disable SLI, I guess one would not have to remove one video card to test the performance gain with and without SLI.

There is also an Nvideo application, Ntune, which will tune your system and graphics card to get the best performance.

But as always do what is best for you!

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After a considerable ammount of experimenting I have concluded that SLI does exactly nothing for FSX.

Even the dual card (9800GX2) even seems to recognise only half it's available memory.

Currently I have a 285 with 1 gig and have decided this is the best card I have ever had.

I would say you would be wasting money buying a second card for FSX

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Interesting finding Jack.

I wonder if the gurus could confirm that ... ie. that with a dual card (9800GX2), FSX only recognises half (512MB) of the available 1GB of memory.

If this is the case, I'll have to seriously consider upgrading my GPU, which I had assumed was using the full 1GB.

Cheers

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Wolter is right.

I had two 9800 GX2's in quad SLI and thought I was doing great.

After a discussion on the forum, I took one out and found that my frame rates actually increased and the sim ran smoother.

9800 GX2's are an SLI card anyway (2 x GPU's bolted together) but I am now firmly convinced that running SLI for FSX is an utter waste of time and money.

My next buy will be a 300 series single GPU model with 2 GB Ram at least.

Frank

I can confirm that FSX only recognises 512 MB of Ram on the card because Windows does as well, even tho it's a 1gb card.

Don't know why?

Frank

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Hi Guys

The other point that many people seem to forget is that the newer GPUs with  >896MB, ie 1+GB VRAM place an enormous load on a 32-bit OS and may contribute to more OOM issues.  Thay can mop up a large proportion of the Virual Address Space which may not leave too much for FSX to operate in. They seem to be more suited to 64-bit OS's particularly the newer ones which address memory differently. Just a thought.

Regards

PeterH

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Wolter is right.

I had two 9800 GX2's in quad SLI and thought I was doing great.

After a discussion on the forum, I took one out and found that my frame rates actually increased and the sim ran smoother.

9800 GX2's are an SLI card anyway (2 x GPU's bolted together) but I am now firmly convinced that running SLI for FSX is an utter waste of time and money.

My next buy will be a 300 series single GPU model with 2 GB Ram at least.

Frank

I can confirm that FSX only recognises 512 MB of Ram on the card because Windows does as well, even tho it's a 1gb card.

Don't know why?

Frank

Hi Frank

Its because its split into 2 x 512Mb for each GPU and I assume only one is being utilised. I just sold my 9800GX2 to a GTX275 and what a difference especially when AA is enabled in nhancer. I have it set Combined AA at 8xs and has little performance hit while on my 9800GX2 it made a big performance hit couldnt use it. I noticed you have a 9800GX2 on your i7 do yourself a favour and buy a GTX275 as they are under $300 and good value and it really is much better than the 9800GX2 even with other games, AA has little performance hit unlike the 9800GX2, performs better and its quieter too.

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FSX does not use SLI at all in its code. However you can drive higher levels of AA with SLI, but at the detriment of FPS in FSX.

I have 2x8800GTXm's in SLI on my laptop, each with 512MB for a total of 1GB. However, since I have SLI disabled, it appears to Windows (and therefore FSX) as a single 512MB 8800GTXm.

The single best card to get for FSX right now is the GTX285; single GPU, 1GB of DDR3 - perfect.  I think I've mentioned this on various posts for some months now ;)

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John

I agree with you but one caveat - I run a 9800GT at present adequate for what I do in FSX but if I switched to the 285 (would love to) I would also have to upgrade the PSU as my present PSU is OK for the 9800 but not the 285.

So the optimum would be a 285 plus a new PSU at 750w or higher - any comments?

Regards

PeterH

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Hi PeterH

NVIDIA states that the GeForce GTX 285 video cards require a minimum 550W or greater power supply with a minimum +12V rating of 40 Amps. , but again that would come down to what other hardware you are running.

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Thanx jrjim67,

You are right about the twin card setup in hardware devices section of control panel. There is indeed,two @512, making up the 1gb of RAM.

I was keen on the 285GTX, as John has stated for a long time now. I also noted that the 285GTX with 2 gig of RAM is available and was wondering if anybody has an opinion on that card.

I'm saving for an overseas trip at the moment, so I may just wait till I get back and then reassess the situation then.

Frank

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I also noted that the 285GTX with 2 gig of RAM is available and was wondering if anybody has an opinion on that card.

I had EVGA GTX 285 2GB “FTW†for about a month before I RMA-ed it back to Newegg.

It did absolutely nothing for performance with the resolution I use and even though it was factory overclocked the memory was clocked lower compared to the 1GB version because of the amount of RAM.

The 2GB version does seem to have possible problem with power delivery and mine would lose video signal after 15-30 minutes of use –

http://www.evga.com/forums/tm.asp?m=100753927

I ended up grabbing the 1GB version of the EVGA GTX 285 “FTW†with the higher clocked memory compared to the 2GB version (2646 MHz vs. 2448 MHz).

 

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Thanx jrjim67,

You are right about the twin card setup in hardware devices section of control panel. There is indeed,two @512, making up the 1gb of RAM.

I was keen on the 285GTX, as John has stated for a long time now. I also noted that the 285GTX with 2 gig of RAM is available and was wondering if anybody has an opinion on that card.

I'm saving for an overseas trip at the moment, so I may just wait till I get back and then reassess the situation then.

Frank

Hi Frank

From most reviews the only time the 285GTX 2MB benifits is when running a 30" screen which run a monster 2560x1600 resolution anything below that did not benefit with the extra 1Gig. But definitely do yourself a favor and get either a GTX 275 or 285 over your 9800GX2 as I had one and noticed a nice difference especially with high AA, you wont regret it especially with your i7 combo.

   

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Ok, so I'm a little bit confused now. Is the fault of the 285GTX 2Gb with the manufacturer or are the cards not up to scratch?

I run triple head2go, so I guess I'd qualify as using heaps of available video memory (like the 30 inch plus).

Has anybody else had similar probs or is it too early for a comparison with this card?

I really do base most of my purchasing decisions on the intelligence gleaned from this forum, so thanx in advance for all the info, guys, I do appreciate it.

Frank

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  • 2 weeks later...

Ok, so I'm a little bit confused now. Is the fault of the 285GTX 2Gb with the manufacturer or are the cards not up to scratch?

I run triple head2go, so I guess I'd qualify as using heaps of available video memory (like the 30 inch plus).

Has anybody else had similar probs or is it too early for a comparison with this card?

I really do base most of my purchasing decisions on the intelligence gleaned from this forum, so thanx in advance for all the info, guys, I do appreciate it.

Frank

I'm looking at this card as an option too. Can anyone help with advice here? Assuming the card is fault-free at manufacture, will the 2gb 285GTX card really help over a 1gb 285GTX? I am not running a TH2GO, but am using multiple large screens.  I saw somewhere (I think at the OZx forums, that Jack ( jgruschow ) had reported great results after upgrading to a card with lost of memory..

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