2 Graphics Cards In 1 PC? - Page 1
Forum section: electronics / projects

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: April 28, 2013, 04:37:50 pm
content: Hello.today i saw a video and the guy had 2 video cards hooked up on his pc and told that he gets double sli..... First If you hook up 2 video cards you get better resultand second what is Sli ?Thank you

author: olsenn
author_rank: Frequent Contributor
timestamp: April 28, 2013, 04:49:02 pm
content: SLI is NVidia's name (can't remember what the acronym stands for) for the connector they place on their modern cards allowing them to be combined in parallel. Yes, two video cards is better than one; however, it may not be twice as good... it all depends on the efficiency of the combination. Many single-slot cards (including my GTX 590) have two cores connected via SLI internally as well.If you plan on adopting this trend I'd highly recommend not mixing different cards (use two or more of the exact same make and model)

author: Ax_6
author_rank: Contributor
timestamp: April 28, 2013, 04:50:37 pm
content: When you have 2 video cards in 1 pc you have to connect them toghether so that they are able to manage video processing "cooperating". This connection is called SLI by Nvidia and Crossfire by ATI. With 2 video cards you should be able to double the performances, I don't know if that is true or not (I don't think so)

author: Rufus
author_rank: Super Contributor
timestamp: April 28, 2013, 04:59:15 pm
content: Quote from: ChrisGreece52 on April 28, 2013, 04:37:50 pmScan Line InterleavingOne card generates the video for odd scan lines and the other for even scan lines.That is what it stands for and how it was originally done, don't know if modern implementations still work that way.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: April 28, 2013, 05:03:47 pm
content: Thanks for your answers and i am sorry because i realised that it is in the wrong forum topic.Anyway my remaining question is does it help the graphics performance?Ax_6 said that he does not thing so but Rufus said that each one do a seperate job so there maybe is a increase.(i think it is ...) but those things created a new question for me.How can you hook 2 video cards together ?

author: hlavac
author_rank: Frequent Contributor
timestamp: April 28, 2013, 05:09:17 pm
content: This is not a good forum for PCs.Find all about SLIhere

author: mariush
author_rank: Super Contributor
timestamp: April 28, 2013, 05:19:44 pm
content: The data a game uses is loaded in both cards, and the cards talk to each other using a special cable (or through the pci express slots) and coordinate, so each video card creates a part of the image you see on the screen.This is done either by a card processing the even lines on the screen and the other card processing the odd lines on the screen, or a card processes and displays a frame (out of 60 shown on screen every second) while the other works on the next frame and so on.With two cards, there is the potential to get twice as fast graphics performance, but in reality the performance increase can be minimal or maybe just 50%-75% more compared to a single card. It depends on how well the game or the application is made.Also (very simplistically put, in reality it's not quite like this), when two cards are linked together, they have to keep in memory a copy of the other card's video card memory so that they're synchronized, so if you have two video cards with 1 GB of memory, each card will act like they have 512 MB of memory, because the other 512 MB will contain a copy of the other card's data. So games that need a lot of megabytes of video card memory can suffer.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 28, 2013, 08:23:15 pm
content: Quote from: Rufus on April 28, 2013, 04:59:15 pmThey don't. Generating two halves of an interlaced image and then deinterlacing it takes a surprising amount of processing power. Nowadays, they either have one card render all the even frames and the other the odds or use some algorithm to cut the image in two (load balancing it) and have each card render each piece.And you can mix and match cards, although you can't use SLI between two different chipset cards. But you can definitely do that to add more monitors, and it makes a lot of sense if only one or two monitors need high performance.

author: hans
author_rank: Super Contributor
timestamp: April 28, 2013, 08:36:58 pm
content: Quote from: mariush on April 28, 2013, 05:19:44 pmIt's better to say both cards have 1GB memory but effective memory remains 1GB. In very dirty terms, they use the memory in raid 1But indeed.. dual GPU set-up means:- More video outputs- Higher frame rates- Equal GPU memorybut also..- Need a CrossFire/SLI link , plus a motherboard supporting it (not every supports all..)- Twice the power consumption (graphic cards tend to use a lot, especially on cards where it make sense to dual them, which is mid-high range cards with atleast 150-200W consumption)- so double the noise...- You need dual decent bandwidth PCI-e slots, like 2x PCI-e 2.0 16x or PCI-e 3.0 8x slots.. otherwise performance can suffer.- Improvements don't scale perfect in general, maximum out at like 70 to 90%, but that's very extreme.- Not every game runs that much better..Dual GPU's can be great for multi-monitor gaming. But don't be cheap on getting cards with high amounts of memory, because it is required to render the big screens..Other than that, it seems like hassle for a little bit more frame rate, and instead you get a clumsy, loud, hot , power consuming rig.

author: notsob
author_rank: Frequent Contributor
timestamp: April 28, 2013, 09:19:59 pm
content: You need a motherboard with 2 graphics card slots and a BIGGER power supply to run them.AND an application that makes the extra cost worthwhile.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: April 28, 2013, 11:15:27 pm
content: Thanks for your answers also i got anything i needed.But technicaly the cards will be connected in series or parallel (maybe wrong question but....)

author: c4757p
author_rank: Super Contributor
timestamp: April 28, 2013, 11:29:56 pm
content: Quote from: ChrisGreece52 on April 28, 2013, 11:15:27 pmThey are actually connected in series. You take the DVI output from one and wire it to the PCIe port of the second.(I am pulling your leg.)

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: April 29, 2013, 10:08:16 am
content: Thanks i now got the whole thing thank you all guys!!!!

author: Psi
author_rank: Super Contributor
timestamp: April 29, 2013, 11:24:20 am
content: Quote from: c4757p on April 28, 2013, 11:29:56 pmIn the original days of Voodoo2 cards (where the term SLI came from) you actually did that kinda.They supplied you with a 20cm cable with a VGA dsub plug on each end to connect each card together

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: April 30, 2013, 10:08:10 am
content: Cool but dont you think that modern cards are more "compatible" and easy to connect 2 of them together than the old ones? ( i just assume)

author: Jon86
author_rank: Frequent Contributor
timestamp: April 30, 2013, 04:23:26 pm
content: Has anyone mentioned you need an SLI Bridge for this?Also, you could just wire them up to run different monitors. I've got 4 monitors running off two different cards, and they work great.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: April 30, 2013, 04:57:34 pm
content: Had no idea. Thank you.

author: Jon86
author_rank: Frequent Contributor
timestamp: April 30, 2013, 05:04:22 pm
content: No worries.If your two cards are identical and Crossfire (ATI's version of SLI) or SLI enabled, you could buy a bridge quite cheaply on somewhere like Ebay. Otherwise, SLI won't work.

author: marshallh
author_rank: Unknown
timestamp: April 30, 2013, 06:01:47 pm
content: I'd recommend not bothering. Save your money and sell your existing card, buy a new one.I used to run 4x Radeon 5850HD in quad crossfire. It was about a 5-10% improvement over just 2x, so eventually I sold off two.I still run two in Crossfire, on the whole compatibility is not a problem, there are some exceptions (FXAA injectors or Direct3d hooks like ENBseries will not work). FPS in crossfire is about 40-50% better depending on the game engine design.Well designed engines like Unreal 3 have no problem scaling. Old crusty monolithic engines like STALKER's see little benefit.Also, with Crossfire enabled you are forced to accept 2 pixel clocks on the cards out of the 4 possible (each card has two). So when my cards are in crossfire I can't use my 3rd screen. If you are using multiple montiors and wanting to do crossfire do some research beforehand.

author: M. András
author_rank: Super Contributor
timestamp: April 30, 2013, 08:07:48 pm
content: ohh dont forget you can only connect the cards together if they are the same, some boards have that lucidlogic bridge chip which connects them without bridge cables, they can be even different manufacturer's card. but its just shit in my opinion.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: April 30, 2013, 11:07:11 pm
content: Quote from: Jon86 on April 30, 2013, 05:04:22 pmWould you recomend to get another Ati Radeon HD 4600 series card and a bridge?

author: mariush
author_rank: Super Contributor
timestamp: April 30, 2013, 11:55:02 pm
content: No, don't throw your money on a second crap card.You'd get 30-50% improvement compared to just one card, which is too little to matter on modern games. The card probably only has 512 MB of ram, so when crossfired each card will only have 256 MB available, which is kinda small for games nowadays.Just put money aside and buy a 7750 or something better.

author: Jon86
author_rank: Frequent Contributor
timestamp: May 01, 2013, 06:25:23 am
content: No, it's a waste of money in your case I think.SLI is only really useful in top-end cards. Don't bother, just get a new card

author: metalphreak
author_rank: Frequent Contributor
timestamp: May 01, 2013, 12:58:31 pm
content: The original crossfire (ATI/AMD) cards had a special output on the back of ONE card (designated as the crossfire edition) to which you would plug the DVI output of the second normal card.This was killed off in the next generation of crossfire since it was such a pain to handle stock etc.Now, all compatible crossfire cards come with a connection flex cable. Buy two cards, and you have two cables to connect the two together. Generally, they have to be identical cards or atleast from the same generation of chips.Nvidia's SLI is a bit different. You used to have to buy an "SLI" compatible motherboard back when nvidia was actually making motherboard chipsets. It actually turned out to be a driver restriction anyway... If you're motherboard is capable of doing SLI it would have come with an SLI bridge PCB/Cable included (nvidia doesn't package them with video cards).In any case, it's only really worthwhile doing with the most high end cards. Buying two $200 cards new and putting them in crossfire isn't faster than a single $400 card. If you add one later on you get second hand cheap then it's not bad.I have an AMD HD6990 in my main PC, which is actually just two 6970 cores on one PCB with internal crossfire and a pci-e bridge chip. Going beyond dual crossfire is generally a waste of money as it doesn't scale that well beyond 2. Same with SLI.

author: kfitch42
author_rank: Frequent Contributor
timestamp: May 01, 2013, 08:37:06 pm
content: 2 ... hah! Try 8!http://arstechnica.com/security/2012/12/25-gpu-cluster-cracks-every-standard-windows-password-in-6-hours/

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 02, 2013, 11:30:27 am
content: Thanks i might upgrade the card but when i try typing 7750 hd on ebay for example it shows many cards from many manufacturers.First is this kind of card compatible with my motherboard and second what manufacturer should i choose?

author: mariush
author_rank: Super Contributor
timestamp: May 02, 2013, 02:43:56 pm
content: Search for "Radeon 7750", not just 7750. But eBay is a bit risky, the video card is still somewhat new so you won't find too many used cards of this model, so you may only find expensiveAny card that goes into a pci express x16 slot will be compatible with your motherboard. With video cards, you only have to be careful of their power consumption. More powerful cards have power connectors on them that are either with 6 pins or 8 pins.Your power supply should have the plug that goes into such connector, if not you can buy adapters that convert a molex (hdd) connector to one of those connectors. But usually power supplies that don't have by default one of those connectors are too weak to power such high performance cards.The Radeon 7750 may need one of those 6 pin connectors (8 pin plugs from power supply will work) or may not need any.Such cards are here in stores at 80-85 euro:http://www.pcgarage.ro/placi-video/sapphire/radeon-hd7750-1gb-ddr3-128-bit-1/http://www.pcgarage.ro/placi-video/sapphire/radeon-hd7750-2gb-ddr3-128-bit/(just enter in google "345 RON to EURO" and you get the euro value)If you add about 5 euro for postage, I can buy one and mail it to you and you have full warranty and all that, unlike eBay.On eBay you'll find it at about 885$ but they'll ask for 20-30$ shipping so you'll get to about 100$ or about 80-85 euro. Not much saving.If you're interested, I'm willing to sell my Radeon 4850 card that's in my computer now for about 40 euro. It's much more powerful than your 4600 series, I can play pretty much any game at 1920x1200 at good framerates so it will be quite an improvement compared to your current video card.It won't run DirectX 11 only games (Crysis 3 for example and few games that will appear in the future - but most companies will still make their games work with older cards for a long time) and that plus the fact that newer cards use less power is why i'd be willing to sell it so cheaply. I'd like to put some extra money and get a Radeon 7770 Ghz edition at least (about 100 euro)

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 02, 2013, 03:43:55 pm
content: Thank you but i would NOT buy it from ebay of course .. an online web store in Greece e-shop has good products a a very low price.but holly cow!!!! look at the price ... 100 for the 7750 and 160 for the 7770http://www.e-shop.gr/product?id=PER.510797