Friday, January 30, 2015

Nvidia, Nvidia, Nvidia! Why you do this to us?


One of the reasons why I upgraded my graphics card to an Nvidia GTX 970 was because I wanted to try SLI. Nvidia SLI support is known to be better than AMD Crossfire and GTX 970's supposedly low power consumption would make them fit in my small chassis. In this article I'm going to talk about how well my decision has turned out to be.

Firstly, I tested how two of these cards would work together in SLI. I got this opportunity because one of the cards I originally bought have a lot of coil whine, and Amazon sent me a second card add a replacement. I had a lot of time to and the defective card do I used that time for my advantage.

While there were definite temperature related issues with two MSI GTX 970 Gaming cards almost touching each other (I later found out that the second card had a even bigger issue where the second fan on it would not spin up at all), I was even more disappointed to find how bad the driver support for SLI was. Both Call of Duty Advanced Warfare and Far Cry 4 misbehaved and were unplayable without disabling the second card. Additionally, even though Crysis 3 had amazing FPS, it wasn't that smooth. While I'm sure these game specific issues - not sure about Crysis though, as it is quite old - will be ironed out eventually, I felt that, in reality, Nvidia was no better than AMD. The green side wasn't as green as I wanted it to be. Read more about that experience here.

Then there is the well-known input lag issue with Nvidia drivers. This is more of an issue if you have a Korean IPS/PLS panel with no inbuilt scalar. This is because, for some reason, even if you select the scaling option in the driver to be “GPU – No Scaling”, it still seemed to do something it's not supposed to do. People who have the option to test either setting say that for least lag, you have to choose "Display - No Scaling" setting. But since three is no scalar on in these Korean panels like the QX2710 which I currently own, the Nvidia driver restrict user to GPU scaling options. What I can't figure out is, why we cannot choose "Display-No Scaling" option if we are not performing any scaling at all. Basically there is no advantage if getting a Korean panel even if it overclock high. What I'm saying is that the QX2710 hardware is quick because it is dumb (i.e. doesn't perform much signal processing), but the driver adds lag to cancel out that advantage. Disappointed!


Even though that is a specific case, generally Nvidia driver with its default settings can - depending on the title -introduce massive input lag. For best responsiveness, you have to tweak the driver in the following manner. If you are wondering why Nvidia doesn't ship the driver with those settings, that's probably because it can lower the FPS in certain titles and FPS is what sells graphics cards. It is unfortunate that the overall gaming experience (smoothness) cannot be quantified.


Nowadays, Nvidia drivers are bloated because of all the features that they have added. Shadow Play, streaming support,3D vision, PhysX etc. are all contributing to the processing lag. You can uncheck many of the components when installing the drivers but there are some that you have to manually disable, such as the audio drivers and all those services. I need to specially say something about Shadow Play. Everybody says that it doesn't cause the FPS to drop, however it does add a noticeable input lag, and this makes it not very useful for recording rapid action multiplayer FPS footage. Sadness! Still, it is the best thing that we've got at the moment, and all of my gameplay videos – predominantly Crysis 3 multiplayer videos – were recorded using Shadow Play after it was released.

The issues don't end there. GTX 970 has a problem with its memory configuration. It's a long topic of discussion, but I'll try to summarize it. The GTX 970 has 4GB memory. Sadly, all of it cannot be accessed at a uniform access speed. For some unclear reason, the Nvidia engineers have removed part of cache units (1/8th of what's available in a full GM204 chip) and this causes the last 500MB to be accessed slower. Thus they've partitioned the memory to 3.5GB and 500MB partitions to prioritize the access (as in the last 500GB is used only when needed), and this makes both partitions inaccessible at the same time. If a game requires the full 4GB memory, there will be potential performance issues. For people who bought two or three if these cards to game at 4K will be affected the most. In their explanation, Nvidia has released performance numbers between GTX 970 and 980 to show that this weird memory structure doesn't affect average FPS in any tangible way. However people who have had the memory usage exceed 3.5GB say that it starts to stutter after that point. Stutter, or rapid fluctuation of frame rate, is much more irritating than low steady FPS.

This unveiling of the actual architectural diagram has caused a lot of controversy. The originally released specs don't tally with the newest anymore. There have been reports of people returning perfectly working GTX 970s stating false marketing, especially in the EU where these laws are very strict. I have no idea about the legal outcome of this, however Nvidia has pledged to release drivers with an improved memory allocation algorithm to boost the GTX 970's performance. However I doubt that most people will be able to notice any improvements with those optimized drivers because this whole memory setup would only become an issue in a limited set of scenarios. Nvidia should give couple of free games for all users of GTX 970s instead.

I definitely won’t be facing the memory problem, because I give more priority to overall performance and responsiveness, thus do not usually crank up the details. However, I am really disappointed in Nvidia this time around because of all these issues and am planning to switch to the red team once the 300 series comes out. Until then

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