The Great SLI Conundrum

If you've followed my blogs much, you know that I'm a big fan of a little-known utility called DirectX Tweaker. I consider this to be an absolutely essential download for any PC gamer, as it has a drastic impact on the performance and visual quality of games.

This all has to do with VSync and a feature called triple buffering. We're all familiar with the phenomenon of "tearing" in videogames. It essentially happens when frames are being sent at an asynchronous rate with the monitor. The result looks something like this simulated picture.


VSync is an option in which the graphics card times the display of the frame with the monitor's refresh rate. However, VSync can cause a significant drop in performance, for a simple reason. Say you have your monitor's refresh rate set at 60hz. The card generates frames and sends them to the frame buffer. There are always two frames in the frame buffer – the frame being displayed (the front buffer), and the next rendered frame (the back buffer). This is called a double buffer. Now, when VSync is enable, before the card can swap the frame buffers, it has to wait for the next Vertical Blanking Interval on the monitor – at 60hz, that occurs every 1/60th of a second. If your card is able to render 60 or more frames per second in the game, everything will look great. But if the game is too graphically intensive for the card to render that many frames, a Vertical Blanking Interval will come, and the frame will not be ready. The result is that the card has to wait another 1/60th of a second to display the next frame. The real-world effect is that your frame rate gets cut from 60 to 30.

Triple buffering adds a third frame in the buffer, so when the vertical blanking interval is ready, there's always a frame to display. The effect is that when triple buffering is enabled, you can get the high image quality of VSync without sacrificing frame rates.

Triple buffering, however, cannot be forced in DirectX games without the use of DirectX Tweaker (it can be enabled in OpenGL games via the nVidia control panel under "3D Settings"). When I discovered DirectX Tweaker, it was a revelation. I can tell you unequivocally that the image quality improvement is HUGE. I also believe that those who say "Gee, I never really notice image tearing" are simply people who haven't seen the other side of the fence. The difference is quite significant.

But, I called this post the SLI conundrum, and here's where it gets messy. Whether it's a driver issue or a hardware issue, I do not know; but for whatever reason, triple buffering simply cannot work with SLI systems. SLI systems can net a significant increase in frame rates in many games. But unfortunately, you will have to choose between the high frame rates of dual-graphics cards and the drastically superior image quality that triple buffering offers.

This may seem like a minor quip to some, but it's enough to convince me that SLI is just not worth the money. I often find myself disabling the second video card just so I can run DirectX Tweaker and get rid of the screen tearing. It's quite disappointing to spend hundreds of dollars on a dual graphics card setup only to find that you have to choose between having image tearing or being locked at 30 frames per second. I'm still trying to sell my current rig, and still planning my next; the new generation of graphics cards are much more powerful than I had anticipated – nVidia's 8800GTX is a huge leap over the 7900GTX (more than double the power, and with far superior image quality), and I'm sure ATI's forthcoming card will be a monster as well. For those reasons, I believe that the best current option for gamers is to simply buy the best single card you can afford.

Then download DirectX Tweaker. Enabling triple buffering is very easy, and the improvement in the image quality is fantastic. In case the point hasn't been driven home yet – it's essential!

Talk about getting bent out of shape!

A little while ago I noticed that when I had two cards in my system, I would get massive slowdown at random times. I couldn't figure it out. I'd be playing a game – any game – and it would slow to a crawl, then a moment later be smooth as butter. This wasn't the usual gameplay-oriented kind of slowdown either. I could be standing still in a place where I was getting well over 60 frames per second, and the frame rate would all of a sudden get reduced to nothing.

At first, I just reinstalled the drivers and ran Driver Cleaner. It looked like the problem was solved. But lo and behold it happened again. I went through a litany of fixes – reinstalling the chipset drivers, reinstalling games, cleaning the registry, defragging, disabling the nVidia firewall, alternating the cards in different slots, etc. Nothing worked. Any time there were two cards in there, I got these massive hits to the frame rate.

Well, I was playing Oblivion tonight, and it happened again. Out of frustration I decided to just remove the card. It was then that I noticed it was really hot. Like, unusually hot. I stuck it back it, and using a piece of paper I discovered that the fan on the Zalman vf900 wasn't spinning. Can you say wtf? I know I had enough power going to the fans – I have a 700w power supply for crying out loud.

I removed the card and discovered that the heatsink was in fact warped, preventing the fan from spinning. The frame rate was dropping because the card was overheating and hitting the slowdown threshold. How this happened, I haven't got a clue. To fix it, I simply grabbed some needle-nose pliers and used the rubber handles to gently hammer the heatsink back into place so that the fan could spin.

Problem solved, but man what a pain in the butt! Now I can enjoy my frickin' rig!

The beauty of PC mods

I thought I'd do something a little different today. I snapped a bunch of photos in Oblivion, with some slight differences. First, I took the screenshots as the game normally is at default, then I took a snapshot at the same point in the game at the same in-game time with the all of the Max Tael mods enabled, as well as the uGridsToLoad setting in the .cgf file increased to 9 from the default of 5. Check out the difference in visual quality (click for a larger shot):













Pretty cool, huh? And remember, these screenshots were all taken at the same in-game time, so I'm not using the normal variations of sunlight at all. The lighting and color saturation are obvious improvements, but if you look closely you'll see more subtle improvements as well, like wildlife, improved water quality, bigger foliage, etc.

It goes to show that if you're willing to take the time, you can get a lot more out of your PC games than you might think.

SLI: Fading into obsolescence

Dual-card setups have become extremely popular among enthusiasts over the past couple of years, and it's a good thing. Well, for nVidia and ATI, at least. It's usually enough of a thrashing to the wallet to buy a single high-end video card, but two? You can easily spend over $1200 on graphics cards alone.

There are two reasons why SLI has become popular. One reason is the rapid advancement in videogame graphics, with games like Doom 3, Half-Life 2, FEAR, and of course the mother of card-crunchers, Oblivion. But the bigger reason why SLI is so popular is because of the rapid decrease in cost of high-resolution widescreen monitors. Just a few years ago, it was unusual to hear of anyone playing games higher than 1024x768. Nowadays, it's quite common to see resolutions of 1650x1050 widescreen. Monitors at a whopping 1920x1200 can be found for well under a thousand dollars. And for the truly elite gamers, there are monitors that max out at 2560x1600.

Until recently, it was simply impossible to play games at maximum settings at these super-high resolutions using a single card. Even high-end dual-card setups often struggle with games at resolutions higher than 1650x1050.

Well, that's all changed with nVidia's newest uber-cards, the 8800GTX and 8800GTS. A single 8800GTX is, incredibly, faster than two previous-generation 7900GTX cards in SLI. What this means is that any game available now can be easily maxed out at most resolutions with a single card. Tomorrow's games are sure to stress the card more, but it's clearly a force to reckoned with. And with rumors that ATI's forthcoming uber-card could be even more powerful than nVidia's offering, there simply is little reason for a dual-card setup with the 8800 series.

The other side is that SLI carries with it a number of caveats. You can't enable triple buffering to get rid of the frame rate drop with vSync; drivers are often incomplete or inadequately optimized; and performance is very rarely double that of a single card, even though the price is.

As the declining prices of high-quality monitors continue to push them into the mainstream, they will become more and more common, and graphics cards will be equipped to deal with them. nVidia and ATI however have made bundles of cash off of their dual-card setups, so I don't expect them to disappear. I think, on the other hand, that they'll be relegated to an increasingly small niche of gamers with extraordinarily expensive gaming setups. Even now, with nVidia's new G80 cards, there's no reason at all to build a system with two cards unless you want to play all games maxed out with high anti-aliasing at 2560x1600.

Driver Cleaner: Not Useless

I was just on a forum the other day giving a guy advice about how to fix repeated freezes during his games. He said he was installing the latest drivers, but he didn't know you were supposed to uninstall the old drivers first.

I explained how to do this, then mentioned that I thought programs like Driver Cleaner were pretty much unnecessary.

Foot, meet mouth.

I've been having problems with my SLI setup. The frame rate would randomly slow down, then go back to normal, then slow down, then back to normal, and on and on over and over. It was pretty annoying to say the least. I tried multiple drivers and nothing worked, and it wasn't isolated to any specific game.

So what did I do? Just on a crapshoot, I uninstalled my drivers, ran Driver Cleaner, then reinstalled my drivers. Guess what? Problem solved.

So hey, Driver Cleaner isn't useless at all. It's the shizzle. Don't upgrade your drivers without it.

BSOD and a fried sound card

Well, I suppose that there's no escaping the BSOD. Rather than try to describe what happened, I'll just tell it as it happened.

I'd had the second graphics card out of my system for a while. Honestly, I got sick of not being able to use triple buffering (plus some strange glitches in Oblivion); and although you can just disable the second card, with my newly uber-overclocked system I was wary of having excess heat.

The other day I downloaded Neverwinter Nights 2, which is a great old-school Western-style RPG. It is a very poorly optimized game (steep system requirements for an average-looking game, mainly due to the use of some heavy shadowing), so I stuck in the second card to get better frame rates.

Now, I'd been using the 91.33 beta drivers because the 91.47's had caused me some minor trouble. For whatever dumb reason, I put the 91.47's back in when I reinstalled the drivers for SLI.

Okay. So, then last night I notice there's no audio. Then the PC freezes. Strange. I restart and everything's fine. I shut down and get ready to leave to see my girlfriend. On a whim I decided to boot up before I leave just to see if the error repeats. Well, when I boot I get the BSOD (I forget the exact error). I restart, but now the computer won't POST.

So I'm thinking there's a big error because of nVidia's shitty 91.47 drivers, which have caused me much headaches. I knew if I couldn't access my BIOS, I'd have to manually clear the CMOS, re-flash the BIOS with the latest update, then manually input all my custom settings again.

Well, I crack open the PC to find a leak in the cooling system. A decent amount of coolant pooled on the sound card. I use alcohol to wipe the graphics cards, northbridge cooler and sound card clean. I then find the leak – one of the fittings for the heatsink wasn't screwed on tightly enough. I tighten it with a wrench and boot the computer just to make sure there's no more leakage. Everything's fine.

I boot back up, and still have the same problems. I even get the BSOD again. I remove the sound card, uninstall the drivers, and reinstall the 91.33 drivers that are so much nicer. Everything's working again. I shut down a reinstall the sound card. The system doesn't POST. I try again, and get the BSOD.

So, it appears as though my sound card is officially toast. I use a non-conductive coolant, but the reality is that an unchecked leak can still cause damage because no fluid has zero conductivity. I'm lucky that my graphics cards and motherboard are okay. Fortunately I'll be able to get the bad card replaced. However I've certainly learned my lesson about liquid cooling. You really have to make sure you've checked and sealed everything.

Oh, and incidentally, my PC only runs 4° warmer overclocked than not overclocked, and having the second card in there doesn't appear to affect temperatures.

2.94ghz!

The main reason I purchased the Swiftech cooling system with a 120mm radiator was for noise reduction, and to clean up the inside of the case. The pump is smaller and quieter than the Asetek pump, and obviously a 120mm fan is less intrusive than an 80mm fan.

But when you've got one of the best cooling systems money can buy, it's hard not to try to push the processor just a bit more. And push it I did.

Previously, I was maxed out at 2.8ghz. Not a bad overclock at all for the AMD 4000+, but even with the Asetek system temperatures prevented me from getting a stable overclock beyond that. With the new Swiftech system though, I've had much lower temperatures. So, for the first time in a long time I dipped into the BIOS settings.

I'm a little confounded by the voltage regulation on this system. Essentially, it caps the voltage at 1.4v, regardless of where you set it (it can be lower than 1.4v, but no higher). The only way to get higher voltage is to enable vCore over-voltage in the BIOS options. This adds roughly 200mV; so instead of 1.4v, it runs at around 1.6v (it fluctuates just a little). It appears to be impossible to increase the voltage beyond this. Bummer, because if it were I have little doubt I could have the system stable at 3.0ghz.

As it is though, I enabled overvolting and managed to get the processor to a rock-solid 2.94mhz. That's a 540mhz overclock over the stock speed. Extended testing in Prime95 has confirmed that indeed this is a totally stable overclock. I'm elated. Not only is my system quieter, better looking, and cleaner on the inside than ever before – now it's faster, too!

What defines "quiet"?

I've been using a Bluegears B-Ice fan in my case for a while now, which I really like because it moves decent air and it's virtually inaudible. But I wanted to try another that I thought might move more air, so I ordered a Link Depot 120mm LED fan. The packaging said it was quiet. The customer reviews said it was quiet.

I put that sucker in my case, and it was like someone just turned on a freakin hair dryer. Well okay it wasn't that bad, but it made me wonder just what exactly defines a quiet PC these days?

While my PC is running I can hear the low hum of the water pump, and the whir of a few fans. It's got sound-dampening foam, and all of the fans are relatively quiet. I say relatively, because I've been through a lot of fans. I've used Sunon, Scythe, Zalman, Thermaltake and Link Depot case fans in addition to the stock Lian-Li fans. I've used a Zalman air cooler that was marketed as "quiet", and now I use a water cooling system. I've used graphics card coolers with stock coolers and the current Zalman vf900a I use.

I don't know what kinds of PCs people are used to, but I think a quiet PC should be, you know, QUIET. Using 120mm fans helps since they move more air at lower RPMs than 80mm fans, but even 120mm fans can sound like hair dryers – much like my Thermaltake when it's on full blast (it's very quiet on medium).

There's also the pitch that you have to take into account. If you have a 60mm and a 120mm fan at the same decibel, the 120mm fan will sound less intrusive because its noise is at a lower pitch.

So yeah. I've gone through great strides to make my PC quiet, including water cooling. Let me tell you, the low hum of the pump is much easier on the ears than the high-pitched whir of a CPU fan. I have to wonder just how loud PCs have gotten if some people are calling fans like that Link Depot fan "quiet", when compared to what I'm used to it sounds like a Mac truck.

And on the seventh day, he rested

It's done! All the renovations are now complete, the PC's back up and running, and it's better than ever.

I did make one minor goof though--I installed the front USB port plug incorrectly. It was probably just off by a pin or something. I didn't know until I tried to plug my camera in. Oh well. I have the rear USB ports plugged in, which I haven't used in a while. I may remove them though. The cord sits uncomfortably close to the Zalman cooler.

On the awesome side though, I've netted about a 9 degree drop in idle temperature on my PC, from 41 down to 32--and that's with the fan on low. It's conceivable now that I might be able to continue to boost processor speed safely and easily. Not only that, it's significantly quieter.

Two final thoughts: The coolant looks green, but it's not a dye. It's MCT-5. Also, if I make any change at this point, it would be to go back to ribbon cables. Round cables are a pain in the ass--bulky and unwieldy. With ribbon cables, they take up less space and you can just fold them whichever way you want.



Anyway on to the pics. If you've been reading my blog for any length of time, I think you'll agree that the PC's never looked better than it does now.

A work in progress...


Almost done...


A look at the innards. I spent a good couple of hours on the wiring.


Up and running!


For reference, here's a pic of when I first put it together back in May, and a pic of how it looked with the old Asetek system.

An inch away... literally!

Sheesh. I've been toiling away for hours on my PC today. I cut a second 2" hole for wiring. I cut a 4-1/2" hole for the fan/radiator setup, which works perfectly and looks great. In case you're wondering, a 4-1/2" holesaw is the proper size for a 120mm blowhole. The fan and grill fit it exactly.

Anyway, I've been building it, and the wiring is the best it's ever been. The cooling system fits really well, and overall everything just looks fantastic. There's more stuff in there and it will perform better, but it looks more open and clean on the inside. I'm so excited about finishing this.

But here's the kicker. Remember the tubing gaffe I mentioned in the earlier blog? I didn't realize PVC tubing was sold by the foot, so when I thought I was ordering two sets, I was really ordering a measly two feet. I thought it might be enough, but alas I came up literally ONE INCH short of the tubing I need to finish. That means the whole stinkin' project has to be delayed until tomorrow. I'm just going to head over to Home Depot first thing tomorrow. I'm sure I can get PVC tubing there.

Otherwise, I'm happy to report that things are just looking fantastic. I've come up with some cool ways to route wires, and the result so far is that everything looks really professional. Hell, I'm going to go so far as to say that most boutique vendors don't do wiring this good. Don't believe me? Just wait. Tomorrow, when I finish, I'm going to show it off in pictures here on the blog.

Quick Update

Right now my PC is in about a million pieces on my desk. I'm waiting to get the proper drill so I can cut a 120mm hole in the top of the case (the arbor for the holesaw didn't fit either of my drills). The Swiftech cooling system is mostly ready to go, and it looks like I have a buyer for the Asetek system. In addition to the 120mm blowhole, I'll be cutting a second 2" hole in the frame for wire routing. The position of the radiator will obstruct the current hole somewhat. I was bummed until I realized I have plenty of space to just cut another. That means I can make the wiring look ridiculously good. The radiator will, however, render at least the top DVD drive slot useless. Combined with with drive bay that will be used for the pump, it's pretty tough to have room for expansion in this four-drive chassis. A dual DVD-drive system may be possible, but it's hard to say.

I have one minor gripe with the Swiftech system, which is that the pump/reservoir setup doesn't have any kind of plating in the front where it'll be set in the drive bay. It's too wide for me to leave the regular plate in to make it look nicer, so it looks like I'll have to settle for being able to see the system whenever I open the front door on my PC.


p.s. Performance PCs did send the pump, but they have yet to resolve the issue with the damaged side panel. The tubing issue was my mistake--they sell it by the foot, so when I selected "2", I was selecting 2 feet, not two sets.