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bagman
05-01-06, 05:40 PM
Hi there
I currently am running a 7800GTX (256mb) with an AMD 64 4000+ and 2gb of PC3200 RAM
I'm thinking of adding another 7800GTX to enable SLI.
My question (and it might sound overly simplistic to all of you) is would 2 X 256mB cards running in SLI mode be equiv to 1 X 512mb card ?
Another factor to consider is the single 512mb card would run in 16XPCIE whereas the 2 X 256mb cards would be stepped down to 8XPCIE.
Would that make any difference ??

cheers and many thanks for your advice

jAkUp
05-01-06, 05:47 PM
No it would not, each card needs to write to the framebuffer, so you still only get 256MB of usable ram.

bagman
05-01-06, 05:51 PM
jAkUp
Thanks for the reply.
Without taking too much of yur time, could yu please give a brief explanation of the benefit of SLI ??
I was thinking that using 2 x 256mb cards would give me better FPS over a single card. Is my thinking way off ??

cheers

Redeemed
05-01-06, 05:58 PM
jAkUp
Thanks for the reply.
Without taking too much of yur time, could yu please give a brief explanation of the benefit of SLI ??
I was thinking that using 2 x 256mb cards would give me better FPS over a single card. Is my thinking way off ??

cheers

No, you are correct. Just that 2x256 for SLi does NOT equal 1x512Mb. The videocards do NOT share ram when in SLi- each card can only use what ever ram that is on that card. If you had 2x512MB cards, each card could only use the 512Mb on that card.

But, yes, SLi will give you quite a boost in framerates- in MOST cases. In fact, in CoD2 there is an option to enable SLi Optimizations. If you can afford another 7800GTX- get it. It'd be faster than a single 7900GTX or 512MB 7800GTX.

bagman
05-01-06, 06:23 PM
Once again, many thanks for replying.

So just to get this clear in my head..... based on the fact that I am not upgrading my 19" LCD anytime soon, a 512mb card would be a waste ??

2 x 256mb cards are going to give me higher FPS in most games, but not necessarily higher textures ??

So if I've read yu guys right, 2 x 256mb cards are better than 1 x 256mb card for an increase in FPS if I intend to remain in 1280 x 1024 ??

cheers and thanks for yur patience

Redeemed
05-01-06, 07:01 PM
Once again, many thanks for replying.

So just to get this clear in my head..... based on the fact that I am not upgrading my 19" LCD anytime soon, a 512mb card would be a waste ??

2 x 256mb cards are going to give me higher FPS in most games, but not necessarily higher textures ??

So if I've read yu guys right, 2 x 256mb cards are better than 1 x 256mb card for an increase in FPS if I intend to remain in 1280 x 1024 ??

cheers and thanks for yur patience

Yeah, I'd say that's close enough. In some situations, the 512MB or ram might be rather useful and allow for an increase in resolution of detail. But in most cases, dual 7800GTXs would be the best bet for performance.

SH64
05-02-06, 08:35 AM
So if I've read yu guys right, 2 x 256mb cards are better than 1 x 512mb card for an increase in FPS if I intend to remain in 1280 x 1024 ??

Correct.

AliceCooper
05-02-06, 02:45 PM
Originally Posted by bagman
So if I've read yu guys right, 2 x 256mb cards are better than 1 x 512mb card for an increase in FPS if I intend to remain in 1280 x 1024 ??
Correct

Wrong, wrong & wrong again. Here's a quote from *****3d.com;

"For a consistent comparison, we ran all the Quake 4 tests at High Quality. As you can see, the only gain from going to SLI is at 1600x1200 with 4x AA and 8x AF. The results seem rather odd; we expected SLI to show off a little more. We even cranked up the eye candy to Ultra Quality and 4x AA / 16x AF, but the SLI configuration only outperformed the single 7900 GTX by about 7 frames per second."

At 1280x1024 SLI will not really give you a great boost in frames. It will allow you, however, to maintain high frames with high AA & AF. But, if you have spent all that money on a new card you will not really get that "wow" factor.

At best SLI might give you 20 to 25% boost in some games but it has cost you 100% more!!!

Look around the forums. Most concensus of opinion states SLI is only worth it if you game at 1600 and above. As you don't (I have a 19" LCD also) it is not really worth the money.

If you really want to spend the money look at 2 x 1gb ram or maybe Raptor H/D as they will speed things up, loading etc. and reduce any stuttering. At least you will see an improvement.

Also, I have a 512mb 7800GT and I really think the extra Vram makes a difference. Gaming is so much more smoother than with a 256mb card. But that is my opinion and is subjective.

Next time you post list your components so people can help you more.

Cheers
:D

Redeemed
05-02-06, 04:08 PM
Originally Posted by bagman
So if I've read yu guys right, 2 x 256mb cards are better than 1 x 512mb card for an increase in FPS if I intend to remain in 1280 x 1024 ??
Correct

Wrong, wrong & wrong again. Here's a quote from *****3d.com;

"For a consistent comparison, we ran all the Quake 4 tests at High Quality. As you can see, the only gain from going to SLI is at 1600x1200 with 4x AA and 8x AF. The results seem rather odd; we expected SLI to show off a little more. We even cranked up the eye candy to Ultra Quality and 4x AA / 16x AF, but the SLI configuration only outperformed the single 7900 GTX by about 7 frames per second."

At 1280x1024 SLI will not really give you a great boost in frames. It will allow you, however, to maintain high frames with high AA & AF. But, if you have spent all that money on a new card you will not really get that "wow" factor.

At best SLI might give you 20 to 25% boost in some games but it has cost you 100% more!!!

Look around the forums. Most concensus of opinion states SLI is only worth it if you game at 1600 and above. As you don't (I have a 19" LCD also) it is not really worth the money.

If you really want to spend the money look at 2 x 1gb ram or maybe Raptor H/D as they will speed things up, loading etc. and reduce any stuttering. At least you will see an improvement.

Also, I have a 512mb 7800GT and I really think the extra Vram makes a difference. Gaming is so much more smoother than with a 256mb card. But that is my opinion and is subjective.

Next time you post list your components so people can help you more.

Cheers


Good point. For some reason, when he stated what resolution he was gaming at it slipped by me. My apologies.

For 1280 x 1024 you would be BEST off with a single 512MB card, and if possible 2GB of ram. If you were to be playing above 1280 x 1024- then SLi would be more worth it.

Again, my apologies for the confusion.

john19055
05-03-06, 05:32 AM
But two 7900GT in SLI is going to be faster in nearly ever game then just with one 7800GTX 512mb.

mon
05-03-06, 04:26 PM
so let me get this right if you have 2x 256 7800 gtx only one 256mb on card is used? yes or is both used .. and windows only sees your cards as 256 not 512mb

? confused also if you only get 20 - 25% ON SLI MODE .more speed why do the scores double in F.E.A.R test? IN SLI MODE

Daneel Olivaw
05-03-06, 09:46 PM
It really depends on the game.

First off, the lower the resolution, the more CPU bound is the performance.
In those cases, SLI just won't change anything since the CPU is just unable to send enough frames to the vid card.

Using very high AA and AF, and playing crazy demanding games like Fear and Oblivion, or running at very high resolutions, then SLI comes in handy.

And forget about video card RAM. 256 vs 512mb and such and such is not the major concern in terms of 3D performance. It is a concern, just not as much a big one as you're making it.

Read up on SLI (HardOCP.com is as good as any place to start), the idea isn't about the Ram, but about splitting the screen up in smaller parts (or alternating the load) between cards.

john19055
05-04-06, 01:11 AM
Still if you Have two 7800GTX 256mb in SLI ,it may just show as 256mbs ,but you are able to use both GPU's processing power, one will be rendering half the load and the other one will render the other half of the load.therefore makeing it easier to render the whole frame at higher resolutios since you have two GPU's doing the work versus one 7800GTX GPU with 512mb,doing the same work load.

Redeemed
05-04-06, 01:12 AM
And forget about video card RAM. 256 vs 512mb and such and such is not the major concern in terms of 3D performance. It is a concern, just not as much a big one as you're making it.

This is *mostly* true.

Some recent games (Doom3, Quake4, BF2, Oblivion, and some titles yet to be released) DO benefit respectably by 512MB of ram. Then again, if you are running a rig with 2GB of system RAM and dual 256MB vid cards, then that would suffice also (in most cases). But, in that sort of situation, the 512MB video card (or even two of them) is the better route.

john19055
05-04-06, 01:37 AM
I would agree also that two 512mb cards in SLI would be better then two 256mb in SLI ,but IMO I still think you would be better off with two 256mbs cards in SLI then one single 512mb card in most all games unless the game is cpu limited.

KickAssCop
05-04-06, 05:27 AM
Get a 7900GTX 512

AliceCooper
05-05-06, 01:04 PM
Completely agree with KickAssCop.

With regards to 256 or 512mb Vram, Ghost Recon Advanced Warrrior won't even allow u to game above 1280x1024 WITHOUT 512mb Vram irrespective of your card!

Lots of noises coming out re UT07 being a massive Vram hog too.

Rule of thumb seems to be if you want a card to last at least 2 years or more buy 512mb (as long as it is at least a 7800), if your upgrade path is 12 months or less 256mb will prob do.

Cheers

mon
05-05-06, 04:22 PM
not even if you have 2 x 256 cards in sli? also with the Physics cards coming out i think 2 years is a long time in a year there will be nvidia cards with this built in hardware and 512 standard and possable 1gb cards with Physics ..

also if you had 1 256mb gtx and a Physics card as addon can you not go above 1280x1024 ?




Completely agree with KickAssCop.

With regards to 256 or 512mb Vram, Ghost Recon Advanced Warrrior won't even allow u to game above 1280x1024 WITHOUT 512mb Vram irrespective of your card!

Lots of noises coming out re UT07 being a massive Vram hog too.

Rule of thumb seems to be if you want a card to last at least 2 years or more buy 512mb (as long as it is at least a 7800), if your upgrade path is 12 months or less 256mb will prob do.

Cheers

AliceCooper
05-06-06, 08:27 AM
Mon, the main issue here is two fold;

1. Is 2 x 256mb in SLi better than 1 x 512mb? IMHO only if you game at 1600x1200. Below that you will be dissapointed because you will have spent 100% more on a second card and not doubled your performance. You will be able to run higher AA & AF but many people may not notice the difference.

2. With regards to the PhysX card again you are looking at spending 250 and on first reviews it actually HURTS performance!!!!

IMO buy the fastest single card solution u can afford for gaming at 1280x1024. My Gainward Bliss GLH 512mb suits my needs fine and I will keep this for at least another 12 months.

mon
05-06-06, 01:04 PM
thanks for that but not looking at getting the PhysX card going to wait for the havox fx drivers that nvidia and havok are working on that card is to mutch for the 10 games they have for it and only 1 is good


Mon, the main issue here is two fold;

1. Is 2 x 256mb in SLi better than 1 x 512mb? IMHO only if you game at 1600x1200. Below that you will be dissapointed because you will have spent 100% more on a second card and not doubled your performance. You will be able to run higher AA & AF but many people may not notice the difference.

2. With regards to the PhysX card again you are looking at spending 250 and on first reviews it actually HURTS performance!!!!

IMO buy the fastest single card solution u can afford for gaming at 1280x1024. My Gainward Bliss GLH 512mb suits my needs fine and I will keep this for at least another 12 months.

Stevedroid
05-08-06, 01:05 PM
Mon, the main issue here is two fold;

1. Is 2 x 256mb in SLi better than 1 x 512mb? IMHO only if you game at 1600x1200. Below that you will be dissapointed because you will have spent 100% more on a second card and not doubled your performance. You will be able to run higher AA & AF but many people may not notice the difference.
It's a bit more complex than that, he could spend $500 on a 7900GTX and he wouldn't double his performance either. You have to figure in the fact that he already owns a 7800GTX. I would certainly agree that if you were looking at getting 2x7800GTX straight off the bat versus getting 1x7900GTX then you should go with the single 7900GTX. However, since he already owns the 7800GTX, you have to exclude that cost. When you do exclude that cost from the equation, getting another 7800GTX would result in a much larger performance increase per dollar than replacing his 7800GTX with a 7900GTX.

Of course it gets more complex if he gets the 7900GTX and sells the 7800GTX, but I don't think a used 7800GTX will command that high a price these days so the second 7800GTX will still probably come out on top in a price/performance comparison.