How can I tell if SLI on my lenovo is working?

[chargersrool]

I have the lenovo y510p with gt750m SLI, when i play games only the left vent is blowing air, the right isnt. But when I go to nvidia settings, Its saying sli is detected and not disabled.

 

[ZionZA]

So your SLI setting in the Nvidia control panel is set to "Maximize 3d performance"?

One way to check if it is working is to download MSI Afterburner. It has a monitoring tool where you can check the usage on the two GPU's. Run a game that supports SLI with this monitor running in the background and then just check if both GPU's show usage.