SLI Primer

GFXguy writes "If you are looking to catch up on some hardware learning you may want to check out "SL Why?". It is a short article that goes over the basics of SLI graphics. The article goes over some strengths and weaknesses of this technology as well. It looks like one video card is not going to cut it any more, at least for the hardcore gamers out there. "

Comments

So when....

[Moonlapse]

is RAIVC(Redundany Array of Video Cards) going to come out? I'd like a RAICV10 please.

AFR / SFR error

[dbretton]

Doom 3 runs in SFR, not AFR as the article states.

In the near future...

[TripMaster Monkey]

All the serious gamers will have 2 PCs connected in series to their monitor..one just for all the video rendering, and one for everything else.

Parallel graphics processing

[FirienFirien]

So now we have the addition of parallel graphics cards on top of the already parallel CPUs; we've had parallel keyboards and mice ability for a long time, and parallel fans kinda vaguely came along too. Parallel HDs exist with extra drives, I'm not sure how RAM extensions are accessed but they're probably classable as parallel too. Technology over the past 15 years: pushing an entire computer lab into a single computer. Considering that we'll have computer labs with these computers in...

Other upgrades

[bigtallmofo]

I think it likely after RTFA that other upgrades would give you more of a boost for your money. For instance, setting up an IDE RAID 5 array with a read/write caching hardware RAID controller would give almost everyone a huge speed increase for all of their applications, not just graphics ones.

Even just adding a second fast hard drive and placing your paging file on that with your OS on your first hard drive would give most users a big bump in speed.

I could go on, but I think on a list of 10 things to do, taking advtange of SLI is probably number 9 or 10.

Re:Other upgrades

[bigtallmofo]

I disagree with what you said "These systems do not have any use for a paging file." If you have more than 1 gigabyte of memory in your workstation and you run some variant of Windows, I invite you to test this for yourself.

Just run Performance Monitor (or Performance or whatever your version of Windows calls it) and add the following metrics:

Pages/Sec from the Memory Object
Average Disk Queue Length (total) from the physical disk object

Even if your memory used is nowhere near what your physical memory is, you will notice two things:

1. Your system still consistently uses the paging file
2. Every time your system uses the paging file, your disk queue length spikes

The moral of the story is, you need a fast disk subsystem for your paging file because Windows will use it even if you have 4 gigabytes of physical ram and are only using 256 megs.

As for RAID 0 vs RAID 5 in speed, what you say is true for writes, but not reads.

Some strange claims...

[Thai-Pan]

The article claims first that you need a $250 motherboard to run SLI (apparently a $75 premium for SLI), and second that you need to pay a large premium for SLI-compatible cards, which are next to impossible to find.

I'm running a $160 motherboard with two 6800GTs that I picked up for a good price at my local shop. They did not have a single PCIe 6600 or 6800 board there that wasn't SLI compatible.

Re:Single video card not going to cut it?

[selderrr]

especially with the next generation of consoles coming out. What Sony or MS should do, is sell a PS3 or XBox2 on a PCI card, with possibility to use the PC audio card & storage. Then hardcore PC gamers can still look down on the cheapo console players :-)

Asinine

[Dragoon412]

It looks like one video card is not going to cut it any more, at least for the hardcore gamers out there.

What a stupid comment.

Currently, the best video performance out there is a pair of 6800 Ultras in SLI, it's true, but that's also well over $1000 in video hardware alone.

Meanwhile, single-card solutions like the X850XT PE are capable of chewing through anything you can throw at them with admirable performance.

SLI is a lot like the tablet PC: a solution in search of a problem. Sure, it's a cool idea, but in practice, not terribly useful and very much overpriced.

Compare, for instance, a pair of 6600GTs running SLI:

$175 for each card; $350 total. Another $50 for the premium on a SLI mainboard.

Now you've got additional heat, additional power draw, two seperate cards, and the hassle of dealing with SLI drivers when, for $100 less, you could purchase a single X800XL and enjoy superior performance.

SLI may become worthwhile in the future, but for now, it's the exclusive domain of chumps and the e-penis crowd.

Re:Asinine

[friedmud]

I just upgraded my computer after having the same one for 4 years... which as a CS major (well, I just graduated) is a pretty long time. How do I make my computer stretch so far? Buy upgradeable solutions up front... and that's exactly what I did this time.

I bought an SLI mobo (MSI K8N Platinum SLI)... put the slowest 939 pin Athlon64 I could find (3500+) (the price ramps up significantly passed this point).... then I bought _ONE_ Geforce6800 GT and 1GB of RAM in two sticks (leaving two slots open)... and finally a 535 watt SLI power supply.... Then hooked it all up to a new 19" Flat Panel.

All in all I paid about $1600... which is a little bit but let's look at the upgradeability.

First of all there's the obvious SLI slot. In about a year when 6800GT's are $150... I'll be able to nearly DOUBLE my performance in games. That's a pretty good upgrade.

I left two RAM slots open so I can jam another set of 1GB sticks in there in a year and have 3GB.

The newly announced dual core chips from AMD will work in my current 939 socket... with a BIOS upgrade... so I will be able to again almost DOUBLE my CPU performance (blah threads, blah, I do a lot of compiling and stuff so it will be a big upgrade for me)

So there you have it. I didn't spend a million dollars... but my computer is REALLY future proof. I probably won't do another $1500 upgrade until about 3 to 4 years from now... and like I mentioned I'm a fairly heavy computer user.

So for me SLI is future proofing my system, and I, for one, am grateful!

Friedmud

Re:Asinine

[Anonymous Coward]

"SLI is a lot like the tablet PC: a solution in search of a problem. Sure, it's a cool idea, but in practice, not terribly useful and very much overpriced."

I think in fact, that SLI was a solution to a VERY SPECIFIC problem;

GFX Card Company Guy #1; we can't get away with $1000 for a video card...

GFX Company Guy #2; No, but for TWO video cards... (Evil Laugh)

Re:Single video card not going to cut it?

[MtViewGuy]

I remember when people poo-pooed onboard video as pretty much useless.

But Intel's very latest onboard graphics chipset is fairly good, and the latest onboard graphics from nVidia's motherboard chipsets are getting fairly good, too. Now, if we can just get VIA to upgrade their onboard graphics....

FUD Biased Article with Inaccuracies

[dbretton]

#1) Doom 3 runs in SFR mode, not AFR.

#2) CPU issue is overblown. I'm not even sure if any additional information is truly sent to the processor.
In AFR, the data for each frame is sent to alternating graphics cards. Since the frames would have been processed anyway, there is not any additional load on the CPU than there would be for an identical system with a video card that is twice as powerful as in an SLI system.
In SFR, the same data is sent to two graphics cards. This would be more data, but seemingly require only a smidgen more CPU power. The video cards send the data between each other over a dedicated bridge, and the video cards handle the task of reassembling the image into a single frame.

#3) SLI card cost. 6600GT AGP cards cost more than their PCIe counterpart. 6800 AGP cards cost less. This has more to do with the amount of time in the market than anything else. In 3 months, the prices will be equal.

#4) Stability. "...certain older cards that are said to be SLI compatible have serious stability problems when used with SLI, but, for example, not all 6800 GT cards can be used with SLI". To date, I have not seen a PCIe 6600GT or 6800GT card released which is not SLI compatible. Not all 6800GT cards can be used with SLI, but that has more to do with the fact that many cards are AGP based and older than two months (when the first SLI motherboards were released).

#5) No benefit. "From what I heard, more than a few games realize no FPS gains at all from the addition of a second video card". First, this is rumor. Many games realize no benefit at low resolutions (640x480, some at 800x600) because the games are more CPU bound than video card bound. All the games that are SLI compatible definitely realize solid FPS gains. Moreover, those gains can be "converted" into graphics enhancements (i.e. no need to go from 60fps to 95 fps, but now you can turn on 8xAA or up the screen resolution, etc.)

#6) Dual GPU cards. The author obviously doesn't know what he's talking about here. The Gigabyte dual GPU card is just an SLI solution on a single graphics card. It's (almost) exactly the same as having 2x6600GT cards. It uses the same technology and produces the same results. So what's this viable new technology on the horizon he is talking about?

#7) SLI cannot be forced. Of course it can! The default mode is "no SLI". This can be changed in the configuration options for the card.

Re:FUD Biased Article with Inaccuracies

[Dragoon412]

#5) No benefit. "From what I heard, more than a few games realize no FPS gains at all from the addition of a second video card". First, this is rumor. Many games realize no benefit at low resolutions (640x480, some at 800x600) because the games are more CPU bound than video card bound. All the games that are SLI compatible definitely realize solid FPS gains. Moreover, those gains can be "converted" into graphics enhancements (i.e. no need to go from 60fps to 95 fps, but now you can turn on 8xAA or up the screen resolution, etc.)

Relative to the cost, the performance gain for SLI is negligable. Take a look at the benchmarks - for the $1100+ you'd spend on a pair of 6800 Ultras, or the $750+ you'd spend on a pair of 6800 GTs, you could obtain nearly identical performance with a $525 X850XT PE, with far less wattage and heat.

#6) Dual GPU cards. The author obviously doesn't know what he's talking about here. The Gigabyte dual GPU card is just an SLI solution on a single graphics card. It's (almost) exactly the same as having 2x6600GT cards. It uses the same technology and produces the same results. So what's this viable new technology on the horizon he is talking about?

That Gigabyte single-board SLI implimentation? It's a big piece of crap.

Re:Scalable Link Interface?

[ZagNuts]

I thought SLI stood for Scan Line Interleaving. "Scaleable Link Interface" is completly vauge. Did they change the technology and keep the old name, or is this writer just an idiot?

Upon further investigation it seems that nVidia's SLI stands for "Scaleable Link Interface", but you are correct in noting that it used to stand for "Scan Line Interleaving". They likely wanted to keep the acronym so that people would know what the technology's function was, but Scan Line Interleaving would be non-despcriptive, as their cards don't interleave at all, each renders approximately half of the screen.

Re:Maybe something I'll look into

[way2trivial]

you do realize how spot on identicle they must be?

same revision, same card almost?

ever tried to add a 2nd CPU to a multi CPU system 18 months later?

Re:PC vs Console - TCO

[raynet11]

That's a valid point, I have both x-box and PC for gaming. It comes down to patience, do I want to wait a few years for Half-Life 2 or far cry to be ported to my console or do I want to play it now? If you don't mind the wait then do so, most hard core gamers are not going to wait. I didn't wait for Half-Life two but in case of Doom, I going to wait for the x-box port.

SLI-who needs it?

[Watersharer]

For some of us, SLI is not a new technology, although the current method is slightly different than the old VooDoo SLI. But after years of gaming, one thing stands out to me. You DON'T need the latest and greatest stuff to run games in most cases. Better to use your hardware budget wisely than to splurge on ultra-swank single components.

I run an AMD 1700, on an ABIT mainboard, with an old ATI9600. Not the pro, but the $79 budget card. I have no exotic cooling, just a nice sink and fan. I added a good copper fan unit to the videocard, which came with passive cooling. I use the features of the Abit MB to run the 1700 at 2.11Ghz, and the video got a 80Mhz bump. I see over 70fps in the CS:Source test, and average around 55-60 online. All for about the cost of one video card.

Re:PC vs Console - TCO

[dbretton]

I suppose this may be true if you are a fan of Grand Turismo. However, aside from that, consoles just don't cut the muster. MMORPG and FPS games don't play very well on consoles when compared to their PC counterpart. Even the "greatest" console FPS, Halo, is just mediocre on the PC.

As far as console first development goes...
Here's a list of PC games that are still not released for the consoles: Doom 3, Half-Life 2, World of Warcraft, Everquest 2, Far Cry, Painkiller.

Audiophile insanity vs. gamer insanity

[raygundan]

"No, gamers have always been much worse than audiophiles. "

You're kidding, right? Audiophiles are off the deep end. I don't think you have ever seen an *actual* audiophile-- you're mixing them up with people who like stereos. Audiophiles do things like buy $3000 cables. Or put all their components on 200lb. granite blocks or $600-per-component magnetic levitation dampers to ease vibration. Power conditioners. Huge stacks of tube amps. Subwoofers that require special basement rooms to be built to act as the box.

In the worst cases, the quest for perfect audio goes so far as to become pointless. There's an article I wish I could find for you about one particularly off-the-deep-end audiophile who paid so much for the system he used to listen to classical recordings that had he kept the money, he would have had enough to bring the *actual orchestra* to his house to play for him regularly, for years. Say what you want about huge stereos, but if it gets to the point where you can afford to bring the source home with you, you don't need reproduction.

The worst gamers can't hope to touch this. The most expensive rig on the market with a massive hang-on-the-wall plasma or whatever as your huge monitor is still just a drop in the bucket compared to people who will spend $3000 on three feet of speaker cable. And unlike some of the audiophile quackery, at least a fast machine has measurable performance gains. Try convincing a real engineer that your $1000 power cable makes a detectable difference in sound quality.

For your reference, as a guide to the levels this insanity can reach:

$23,000 for a pair of 8-foot speaker cables

$75,000 per speaker

$40 silver-plated electrical outlet (because... ummm... you can't just use any old outlet with the next item:)

$1000 5-foot AC power cable

There's much worse. Try pricing out monoblock tube amps. Keep in mind they're not just going to buy one per channel (the minimum), but probably one per *driver* (as in, three per speaker if you have a woofer, mid, and tweeter).

Re:Audiophile insanity vs. gamer insanity

[Snommis]

I agree - audiophiles are worse, INITIALLY. But they can usually resell a piece they replace (sometimes at a profit). Us gamers buy a $500 card to trash it 6 months later.

My stereo will clearly play great audio long after I trash my current rig, and a few components after that, too. Until you can purchase an ear upgrade, anyway. The next FPS down the pike will make my PC a paperweight...

Re:Audiophile insanity vs. gamer insanity

[Elwood P Dowd]

That last link is fantastic. Halfway into the article:

I must admit that after I came to appreciate the importance of interconnects and speaker wire, I still didn't think that power cords would make any real contribution to the sound of the system. I'm sure that what happened to me has happened to many others in that after installing a high quality power cord, the sound of my system improved. The major change was in the bass; it became fuller and more extended. At that point, I became a believer in high end power cords.

And in closing:

The largest impact that these cords had on my system was the addition of harmonic fullness and tonal weight. As a result, instruments sounded much more solid and therefore, more realistic. Many systems that I have occasion to hear sound very light and somewhat thin compared to live music. Here, the sound was warm but not overly so. The images throughout the soundstage were well defined and stable. Where there was depth in the recording, it was presented as well as I have heard in my system. There was a pleasant lack of any edge or glare with the Golden Sound cords. Since I tend to be sensitive to these flaws, this was a good thing.

Overall, I have a real appreciation for what the Golden Sound cables can do. If your system is on the dark or overly euphonic side, these might not be the cables for you. If on the other hand, your system sounds somewhat thin, bright or lacking in tonal weight, the Golden Sound power cords could be just the solution. Within the current universe of power cords, the Golden Sound power cords are reasonably priced. Given their effectiveness, they should be considered a bargain.

Re:Single video card not going to cut it?

[deathazre]

well, the xbox has sure put an end to gaming on old celeron 733 machines with old video cards.

wait...

Re:What about...

[randyest]

What about you? There will always be older, cheaper hardware available and you can just get one of them instead of two.

There's one of you in every thread about something new or high-end:

"A cellphone with a camera and flamethrower? What about those of us who just want to make a call?!"

"A GPS that drives for me? What about those of us who just want to download directions ?!"

"A computer with two graphics cards? What about those of us who just want to play minesweeper and read email?!"

I don't get it; does it really bother you so much that there are some people who want more or different performance levels than you?

Do you not realize that the very existence of high-end products helps drive down prices for the lower-end stuff you so desire?

Re:Single video card not going to cut it?

[keeleysam]

I also buy nvidia because of their WINDOWS drivers. ATI's (in my experience), are like HP's printer drivers (awful), and nVidia's JUST WORK, and overclocking is easy.

200-pound granite blocks are great!

[billstewart]

I went to college before CDs came out (:-) so audiophiles back then were optimizing vinyl-player systems. After doing some sidewalk construction on my fraternity house, we were left with a number of big hunks of slate, fairly flat on top and weighing maybe 100 pounds. One of the guys used it as a stand for his turntable, set on top of cinder blocks, and it was fairly resistant to people dancing nearby. He mostly listened to classical music, and while his system wasn't high-end audiophile gear, he'd reached the point that he could pretty much hear anything the orchestra was playing - and spending more money to cut out the next little bit of distortion was nowhere near as effective as getting records of better orchestras with better conductors, because hearing the Boring Strings Orchestra slightly better wasn't going to improve their playing any, while getting Furtwangler or Stachowski conducting the Berlin Philharmonic was going to sound better even if the vinyl was old and scratchy.

I had that room the following year and used the slate as a plant stand :-)