Samsung NP-700G7C-S01UK: all recent graphics drivers cause latency

Hi all

I have a Samsung laptop, model NP-700G7C-S01UK, which uses a GeForce GTX 675M 2GB video card (factory configured without Optimus switching). The laptop runs Windows 7 64-bit, which is a clean install without any bloatware.

I’m having a heck of a time trying to get good low-latency performance from the laptop when using any recent Nvidia driver.

The GeForce graphics card driver that shipped with the system was version 296.01. This appears to be a customised release of Nvidia’s own driver because a search online for the version number turns up only the Samsung laptop, not an official Nvidia release. No driver with that number appears on Nvidia’s website.

The 296.01 driver is old (April-May 2012) so I have been keen to update to a later driver. Samsung being Samsung, they have not released any later Windows 7 graphics driver for the laptop.

However, every single driver from the Nvidia site that I’ve tried (which is most of the WHQL releases that support the GTX675M) causes bad latency. I am using Latency Monitor from Resplendence Software - Advanced System Tools and Developer Components to measure this, and to confirm that the Nvidia driver is the source of the latency.

This is a problem for me because I use the laptop for audio recording, and the driver latency causes interruptions in playback and recording.

So I appear to be stuck with Samsung’s ageing driver, but am unable to tell why that old release should give such different latency performance than any other more recent driver.

I experimented with disabling Nvidia powermizer with the Nvidia GPU Tweak tool but it made no difference to the latency.

I have heard that Nvidia’s expensive Quadro cards have lower-latency drivers but of course that would mean buying a new computer. It’s frustrating that it is clearly possible for a GeForce driver to run at low latency – I just don’t understand what’s so different about the 296.01 driver.

Can anyone shed some light on this? Am I really doomed to use the old 296.01 driver?

Thanks in advance.

(I also posted this at the Nvidia forums and will report back here if I find a solution there.)

 

Have you read the latency thread and tried the suggestions there? (But I do appreciate that this is a specific graphics driver issue).

John

 

Thanks John - but yes, I've seen that thread and it doesn't apply here. I don't have anything else installed on the system that's causing the latency. (I even did a clean install to a separate partition for testing purposes). Latency Monitor traces the latency specifically to the Nvidia driver.

Obviously, removing the Nvidia driver and using the stock Windows VGA driver solves the problem entirely...but then it's hardly worth having a GTX675... :-/

 

R331.65 whql.

 

Hi TANWare, thanks for posting.

That's the current driver, which I'm using, but on my system I get DPC values of at least ~900 from the Nvidia driver. They happen repeatedly, but not regularly.

May I ask how long you left the monitor running for?

 

it say's on the graphic 1:06 how long between these hits do you see?

 

It is apparently random, which is one of the most frustrating aspects of the problem. :-/

At the moment I am getting the ~900 values from Nvidia within 1 minute of launching the monitor, but that isn't always the case.

If you could leave the monitor running for 30 mins - 1 hour, there should be at least one big spike, if it's going to happen at all on your machine.

 

30 minutes, long hardfault is media player share service primarily

 

Thanks for taking the time to test this.

I wonder what would explain the difference. Maybe there is a subtle difference between the S01UK and S01US models of the laptop.

What BIOS version are you running?

Edit: in a ten minute test, it appears that setting screen refresh to 120Hz rather than 60Hz makes a difference. At 120Hz the max latency from the Nvidia driver is approximately halved. However, this may just be a coincidence.

 

If it is halving the times then it probably is a program either making a bad call to capture or put data to the screen. Check all side bar gadgets, widgets, notification area programs. Even ones that can screen capture or updated the task bar etc. Close these down and see if the issues go away.............

 

Hi TANWare

Thanks for the suggestion but I have been seeing this behaviour in a clean install of Windows with nothing running except the latency monitor. :-o

I will test again at the different refresh rate later. Fortunately the latest Nvidia driver allows use of the 120Hz at less than maximum brightness.

 

Do you have Windows System Restore enabled? That one can cause latency spikes as well. And yes, as mentioned by TANWare, absolutely disable Windows Media Sharing Network Service and its UpdateLibrary Scheduled Task.

 

Thanks, I will check those settings. But why would they cause the Nvidia driver to introduce latency? It's that specific driver which is reported by latency monitor as the culprit.

 

Any task or driver trying to make a disk change (even just a log entry) will be delayed by system restore. You probably won't see system restore listed as the culprit.

Or it could be something else entirely.

 

When you say a fresh install of Windows, first off we are talking Windows 7 and second off are we talking with or without all the Samsung software?

 

Hi both,

Yes, it's an install of Windows 7 64-bit SP1 to a new partition with only drivers installed, no Samsung software. I did this installation specifically to test latency.

Dannemand, I don't have those services enabled. I honestly think the issue lies squarely with the Nvidia driver - it's the only thing I'm changing between getting the latency and not getting the latency.

 

Got it, thanks. Yeah I was just throwing in there what I could think of, that might be different between yours and TANWare's system (which doesn't show latency spikes using the same Nvidia driver).

 

Well one thing to try. MSI after burner and set the voltage to max. What could be of issue is the declocking of the GPU to conserve power and keep the GPU cool. As far as the graphics that is about the one thing that could be different other than I also overclock the video..............

 

The reason I suggest MSI afterburner is I use that. The 2D voltage could be an issue. I do know on mine the video card does not seem to cause any latency at all.

 

Sorry for slow reply - haven't had a chance to try Afterburner yet. I will do, and will report back.

Do you know if it does something different to the GPU Tweak software that disables Nvidia Powermizer?

 

Yes, at least force constant voltage. During non gaming to save power and keep the GPU cool with just the drivers it will switch over to a lower "2D" voltage. Force constant voltage should keep the voltage up to 3D levels on the GPU. I doubt this is the issue but it is something I do differently than you.............