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Can a GeForce 9800 GT and a 9800 GTX do SLI?
http://www.wsgf.org/phpBB3/viewtopic.php?f=72&t=18815		 Page 1 of 1
Author:  Zoandar [ 03 Jan 2010, 00:01 ]
Post subject:  Can a GeForce 9800 GT and a 9800 GTX do SLI?
I have an EVGA GeForce 9800 GT 1GB DDR3 in my PC now, and have just acquired a factory refurbished BFG GeForce 9800 GTX OC 512MB card. I would like to know if it is possible to connect both cards in SLI?

The motherboard is an EVGA Nvidia nForce 680i SLI with dual PCI Express x 16 slots.

I don't have any experience at SLI, and on the NVIDIA site it says that to SLI a 9800 GTX one needs another 9800 GTX. But I don't really know the difference between GT and GTX. I am wondering if it might be possible, but they just specify both being GTXs to cut down on support requests?

I would like to try this if it is possible, since I have both cards here now. The BFG just arrived as a warranty replacement for an older 8800 that went bad. They were out of 8800s so sent this. But I had already bought and installed the EVGA card as an upgrade. I figure I might as well use them both if I can.

I looked for SLI info on the forum, but didn't find the answer to this specific question.

Any information will be appreciated.

Zoandar
Author:  Gilly [ 03 Jan 2010, 11:30 ]
Post subject:  Re: Can a GeForce 9800 GT and a 9800 GTX do SLI?
I believe you need 2 *identical* cards to do purely image pushing with SLI, however you could use the GT as a physics card for example, if you were to use the GTX as the image pusher, AFAIK.
Author:  Zoandar [ 03 Jan 2010, 16:54 ]
Post subject:  Re: Can a GeForce 9800 GT and a 9800 GTX do SLI?
Thanks for the quick reply! I am not familiar with what you are describing. Is there someplace you could recommend where I can read about how to do that?

Zoandar
Author:  infernus [ 04 Jan 2010, 16:43 ]
Post subject:  Re: Can a GeForce 9800 GT and a 9800 GTX do SLI?
http://www.nvidia.com/object/physx_faq.html#q4
Second paragraph under "How does PhysX work with SLI and multi-GPU configurations?"
Author:  Zoandar [ 04 Jan 2010, 17:47 ]
Post subject:  Re: Can a GeForce 9800 GT and a 9800 GTX do SLI?
Thanks!

Zoandar
Author:  Gilly [ 04 Jan 2010, 20:36 ]
Post subject:  Re: Can a GeForce 9800 GT and a 9800 GTX do SLI?
I was only stating what I thought they could be used for. IMO going down this route is silly...... don't get dragged into the physics route IMO. Just saying AFAIK you should have 2 identical cards.
Author:  Zoandar [ 04 Jan 2010, 22:31 ]
Post subject:  Re: Can a GeForce 9800 GT and a 9800 GTX do SLI?
I was only stating what I thought they could be used for. IMO going down this route is silly...... don't get dragged into the physics route IMO. Just saying AFAIK you should have 2 identical cards.


Thanks. I appreciate the heads-up. I did read the information at the link which was posted a bit later in the thread. Then I researched whether even having that option would be useful to me, since I only play 3 games which are now considered "old" : Flight Sim X, Lock-ON, and Half-Life2.

I know there would be nothing for a Physx card to render in FSX. In Lock-ON I suppose maybe some of the explosions could use some help, but lets face it, I am thousands of feet away (on a good day) :-)
and passing by them rather quickly, so probably a "no" there as well. Actually I don't know if Physx API is even used with those.

Lastly I discovered that Half-Life uses a competing technology called Havok, so there again I wouldn't gain any use for Physx. So I had already decided against this option.

What I think I will do is just eBay the 9800 GT 1GB and install the 9800 GTX 512 OC and then look into getting another GTX to match it so I can try the SLI. I see that both types of card are still available online.

Thanks everyone for helping me make these decisions!

Game on!

Zoandar
Author:  Paradigm Shifter [ 05 Jan 2010, 19:06 ]
Post subject:  Re: Can a GeForce 9800 GT and a 9800 GTX do SLI?
None of those three games you mentioned take advantage of PhysX. So a dedicated PhysX card isn't worth it.

I'd keep the card with the 1GB framebuffer, and eBay the 512MB card. Of course, this will depend on what resolution you're playing at, as the higher the res the more you'll need the VRAM.
Author:  Zoandar [ 05 Jan 2010, 23:34 ]
Post subject:  Re: Can a GeForce 9800 GT and a 9800 GTX do SLI?
You are addressing one of the things I am hoping to learn here. That being, how much impact on performance does the GT with 1G memory have compared to the GTX with 512MB memory?

When I had sent my failed 8800 GT in for RMA to BFG, I had already bought a replacement, mostly because their statement over the phone that my RMA was approved and "you should get an email with the details within 10 minutes" played out to be 2 WEEKS. After the first week, I decided the RMA process was going to be lengthy (this all started in November) so I started shopping. I found that 8800s are pretty much gone now, and 9800s were affordable. Not knowing what the "X" in GTX really meant, I did see that the card I bought had 1GB of DDR 3 on it, which was the deal closer for me. Had I realized that both GT and GTX models sell for only a small price difference, I might have gone for the GTX, now knowing it has more cores. I have not seen a GTX with 1GB in it which was comparably priced though, so I just stuck with the 9800 GT. I had no idea what BFG would be sending me back (or even IF, at the snail's pace they were handling this). Had I known they were going to send me the 9800 GTX OC, I surely would have bought one just like it to try the SLI.

So how does one decide between the 9800 GT 1GB and 9800 GTX 512? Is it just opinion, or are there some benchmarks somewhere I can read?

As far as what resolution I am using, my TripleHead2Go setup, with the monitors I have, has to run at 3840 (3 x 1280) x 1024. As far as each individual game's display settings, the answer to that is "as high as I can get away with". :-) In FSX I have almost everything maxed out. The same in Half-Life 2. But for some reason, I can't get smooth flight doing that in Lock-ON. It tends to get a little lag, so I had to back off a bit on the settings in that game.

I welcome any comments on which of these 2 cards would likely yield higher frame rates for what I am playing.

Zoandar
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