Thursday, December 10, 2009

NVIDIA SLI & the Flickers

I just wanted to keep all of you curious folks up to date on my latest computer update. Because I know you are all furiously curious.

The computer I built 2 years ago is still keeping up with the latest software so I've seen no reason to build a new computer.

However, as the graphics in games get more demanding I decided to do an experiment. I decided to install a second video card to take advantage of NVIDIA's SLI technology. Basically leveraging the GPU's of two graphics cards to give a performance boost.

My first mistake was assuming the graphics card would come with the little SLI link cable.

I opened the case, installed the new video card in the second slot and turned the computer back on. Voila, the NVIDIA driver detected that there was another video card and set it up as SLI. I was shocked at how easy it was. But then I got an error message about "video link not detected".

My first reaction was to re-check my video card box for a missing cable, but it was empty. My second thought was simply a sinking feeling. Then, I did some research.

It seems the link cable in question is normally shipped with the motherboard. I have an ASUS P5N motherboard and I still had my box so I looked in it and sure enough, there was a cable just like the one pictured above. It's obvious where to connect it on the NVIDIA graphics cards. If you need a diagram, you probably should put the cover back on your computer and carefully back away from the machine.

Then, I ran my first game and I got these bluish artifacts and flickering while running. And I got another sinking feeling. My power supply only had one power plug for supplying power for video. Obviously with a second card I needed another plug. The new video card came with a power plug adapter. You basically had to plug two standard plugs into this one adapter to create one video card plug. All the web sites I visited said that the flickering was more than likely a power problem.

My mistake: I used a standard plug that was daisy chained to a case fan. I took another look in the case, did some power rearranging and produced two dedicated standard plugs to feed the video plug adapter. You might have to read that twice.

I turned everything back on and it's been running flawlessly ever since. It seems smoother, but unfortunately I didn't do any performance tests for a before/after comparison. I don't know that it would have made a difference. When you have two of something it's not always faster, but often times smoother. I don't know that I've seen a performance test that measures smooth.

You see performance tests all the time that say, "I get 60 frames per second", but you don't often see a run over time with various activities where you maintain an average of 40 frames per second with a low of 10 and a high of 60. I suspect that having two GPU's would mostly produce a more stable frame rate with a better average and a higher low, but I don't feel like proving it.

Another thing to do if you intend to try SLI is to go in the NVIDIA control panel and make sure it says SLI is enabled. After experimenting with mine, it somehow got switched to disabled and I had to re-enable it. There was no warning except just to check it and see that it was disabled.


  1. I don't mean to be rude, really I don't, but I'm a fairly happy guy who spends a lot of time on his computer that is, I dunno, 5 year old. Don't you think, maybe, if you looked around, maybe, you could find something a bit more exhilarating to do than sticking a second video card into your computer to possibly see things, maybe, a bit smoother? Perhaps you might consider doing some volunteer work with your free time. Be a Salvation Army Bell Ringer. Read a book. Help an old lady cross the street. I dunno. There's got to be more to life than making a video game maybe run smoother.

  2. Gar, I have a wonderful idea for something you can do with all your free time, much better suggestions than what Durango had. I think you should build Durango a new computer, ya know, since his is 5 years old. He gets a new computer and you get to do something you really like. Voila...problem solved for the both of ya :)

  3. CT2----Thank you for your problem solving, but I don't need a new computer right now. And Gar charges too much for his help. Last time he helped me make a computer I had to buy him roller blades. I agreed to this if he agreed to go roller blading with me. He did so. One time. And got the worst case of the vapors I'd seen him get, up to that point. I think he rolled, awkwardly, maybe 20 feet before he collapsed on a bench, hyperventilating and turning a disturbing shade of grayish green. When he was finally able to speak all he could do was mutter 'need beer, need beer.' That was quite some time ago. I didn't realize it at the time, but his serious drinking problem already existed. I wonder if he's sober when he does his computer upgrades? If not, maybe that's why it takes him so long to do something simple like installing a video card.

  4. He said I was CUTE! (nose glows bright red and now I can fly)

  5. CT2---

    He said "You guys are so cute."

    You are not a guy.

    I think he was referring to me and made a typo, intending to type "You, guy, are so cute."

  6. I suppose you're right, I mean let's face do have a better looking body. And since (i can only take your word for it cuz i didn't get to actually read it) he wanted ED to get a sex change...well...

  7. CT2----
    I don't know where you'd get the idea that I've got a better looking body than you. That's just ridiculous. As for Gar's deleted post where he discussed, at length, his wish that ED would change genders, well, if you read the comments in that deleted post you will read ED and Gar discussing this, with Gar conceding to ED that it is he, Gar, who should switch Gender due to his head start with big Man Boobs and girlish hips.

  8. It's amusing how you guys can degenerate an unrelated blog posting into sex change operations, possible meanings of the usage of the word cute, and moobs.

    Pardon the interruption.

  9. Gar? Did you say something?

    Durango, so from what I've gleaned from your previous comment, it's Gar that has the better looking body, ya know with his man boobs and girlish hips...hmmm, then I wonder why he said guys were cute? Oh! I get it...he's getting the sex change operation! Sorry, it takes me awhile sometimes, ya know, cuz I'm a blonde.

  10. CT2---I can see you have put a lot of thought into this subject. I really don't think Gar's big man boobs and girlish hips indicate he has the best body, overall. But what I think you are saying is that he has the best body to switch genders cuz he's partly already there, without any hormone therapy. His commenting on cute guys is just Gar getting ahead of things and thinking like a woman before he actually becomes one. Well, so much for my random ramblings on this subject for the day.

  11. Mr. Durango, I was wondering if Gar's website ratings have improved since he's stopped, uh I mean blogging about Aquarians and now only blogs about Alcohol and Sex Change Operations?

  12. CT2----
    Last I looked Gar's ranking had gotten worse. An Alexa Ranking of something like 25 million. Meanwhile yours sure has gone up. You seem to resonate with the people. As for Gar's current status, ranking wise, I don't know if it has improved since he stopped talking about uninteresting stuff. His imaginary tales about his imaginary cruise with his imaginary wife likely got more readers than when he blogged about his imaginary wife's horoscope. And all he has had to say about what he thinks about getting a sex change likely interests people, as well. I'll try to remember to check these important statistics tomorrow and get back to you with what I find out. Are you still working on the Intervention regarding the drinking problem?