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I have a laptop running Windows 8 with 2 graphics cards built in, it also has an HDMI slot and a VGA slot.
I'm trying to run two external monitors and the laptop monitor at the same time. One is hooked up to the HDMI, one to VGA.
Is this possible without external hardware?
In the Windows display settings, I see all 3 monitors, but can only apply settings to extend two; but I thought two video cards would make this possible?
prospector
Posted 2015-01-31T21:06:19.410
Reputation: 183
18
This is a hardware limitation.
First off, your laptop doesn't actually have two complete graphics cards. It has two GPUs, but only one is completely wired and all outputs are connected to it. This is true for most laptops with hybrid NVIDIA graphics.
Your laptop's main graphics card is Intel HD Graphics 4000, which is integrated in the CPU. It's always enabled and it's the only device in your laptop that can produce video signal on outputs. When a graphics-intensive application is running, NVIDIA GPU kicks in and starts rendering graphics. Then pre-rendered frames are sent to Intel GPU and it forwards them to outputs. For Intel GPU these are just still images and it's quite good at rendering them, so there's no performance loss.
(By the way, there are also some cases when NVIDIA GPU is used, but frames are rendered by Intel GPU - google "CUDA" or "GPGPU".)
The good news is that HD Graphics 4000 can support up to 3 screens (including the laptop one) under some conditions. The bad news is, these aren't met in your laptop, because internal screen is connected via LVDS cable and eDP connection is required for 3 monitors to work. (source) I know that it's LVDS and not eDP, because you can buy a replacement LVDS cable for this model.
You can buy an external video adapter connected through USB, but this solution is far from perfect. USB adapters have heavy impact on CPU usage and limited throughput, so you may have problems with high resolutions and framerates. I've heard that USB 3.0 adapters work with 1920x1080 screens at reasonable framerates, but I haven't tried it myself.
gronostaj
Posted 2015-01-31T21:06:19.410
Reputation: 33 047
in that case I guess my only option would be going with this? http://www.officedepot.com/a/products/407054/j5create-JUA350-Display-Adapter-USB-30/
– prospector – 2015-01-31T21:59:34.583Your link doesn't work, but from the URL I guess it's what I have described in the last paragraph. It should work, but expect higher-than-usual CPU load and maybe some stuttering on the third screen. – gronostaj – 2015-01-31T22:08:04.673
ok then, I think that will work, im only using the 3rd screen for web browsing and programming. – prospector – 2015-01-31T22:14:13.957
2I got the usb3 hdmi adaptor, everything works great now – prospector – 2015-02-01T01:25:23.540
-1
I'm sorry, but you don't have two graphics cards two work simultaneously. Nvidia Optimus is intended for power saving. For example, some parts of the graphic card works at 2D (desktop, files...) and others does 3D (CAD, games...). More info at Wikipedia Nvidia Optimus.
edumgui
Posted 2015-01-31T21:06:19.410
Reputation: 546
Link isn't working for me... I think you need something like that http://plugable.com/products/uga-165
– edumgui – 2015-01-31T21:51:27.457I have Optimus in my Thinkpad and I can use (at least) 2 external displays + internal at the same time. According to the tool the NVIDIA card gets switched on when the DisplayPort port is used. – AndreKR – 2015-02-01T17:40:35.150
2It probably doesn't work how you think it works. What's your laptop model? – gronostaj – 2015-01-31T21:17:10.727
@gronostaj samsung chronos np700z7c-s01us – prospector – 2015-01-31T21:26:42.310
I have that same setup on my laptop (but with Win 7) and I don't recall having to do anything to enable it. – Jeanne Pindar – 2015-02-01T19:33:43.283