How to buy the best External GPU for a 5GB/s Bandwidth adapter?

[augeacc35]

Hello, I'm using GDC V8.4 Beast adapter for my MSI GT70 laptop. I have a Gigabyte gtx670 (2GB) 3x windforce edition graphics card and I would like to upgrade. I very lately dicovered that the adapter from MPCI-E to PCI-E x16 has a limit of only 5GB/s of bandwidth. Could anyone explain me what does the bandwidth technically use from a GPU? I don't want to buy another card and have like a 35% performance loss comparing to desktop pc. Please don't offer any thunderbolt, because it's not gonna happen. My only alternative would be legit PCI-E to MXM adapter. Besides that, at what should I look when choosing a GPU for this build? Does electricity usage matter much? I believe some really advanced knowledge is required here

 

[t53186]

OK lets get technical. Bandwidth is a term used to describe the amount of data that can move in a given period of time through a conductor. In the case of a GPU the data generated by the CPU that represents what needs to be graphically displayed is sent along a bunch of conductors "PCI Lanes" to the GPU which in turn converts that data to a stream of data sent to the display. So in this case 5GB of data per second is sent to the graphics card. With PCIe x16 you could see a maximum theoretical bandwidth of 8GB/s, so your adapter is decent. Any update would be any increase in performance and possibly a decrease in power consumption (unless you go crazy).

 

[augeacc35]

OK lets get technical. Bandwidth is a term used to describe the amount of data that can move in a given period of time through a conductor. In the case of a GPU the data generated by the CPU that represents what needs to be graphically displayed is sent along a bunch of conductors "PCI Lanes" to the GPU which in turn converts that data to a stream of data sent to the display. So in this case 5GB of data per second is sent to the graphics card. With PCIe x16 you could see a maximum theoretical bandwidth of 8GB/s, so your adapter is decent. Any update would be any increase in performance and possibly a decrease in power consumption (unless you go crazy).

Thanks for your great fast response! I guess it's kinda impossible to calculate the bandwidth stuff. Even Nvidia is unsure about any bandwidths. Just to add, I will write my theory here: Computers reansfer electrons (Voltage and current) so I believe I need to choose as much power efficient card as possible while keeping quite a decent one. Fallowing the formula P(watts)=I(current) * V(voltage) will confirm this. In the end since my whole GPU potencial is only 62.5% ( (100% / 8)* 5), various videos comparising desktop and external GPU confirms that the External GPU FPS results actually are about 35% worse. Thanks anyway and I hope it will be helpfull for everyone 😉