Ive had nothing but issues using the graphic amplifier on the R5, Im probably going to return the system this week as it's within the 30 day window and just buy a replacement motherboard for my R3. Dell premium support wasted 2 hours of my time and accomplished nothing. 

I finally got it to work for some reason the cable will only work one way when I put the cable into the amp the other way around it works . Did not think it mattered but for some reason it did. I am having a random problem now I am not sure if the power supply fan is bad on my amp or if my cards fans are bad . when card is underload there is a high pitched wine noise coming from the amp now. If I go into my card settings and turn the fans to 100 and leave them there don't hear it only when I lunch a benchmark program do I hear this crazy wining noise. right when I end the benchmark. So I am wondering if the power supply is bad ?

I am using the Graphic Amp with my R2 right now, I got GTX1080 installed, and there is no issue happening at all..... I think the power consumption is only a little bit higher with RTX2080, and the Amp should be able to support something like 375W, so it shouldn't be the issue with power supply unless there is something wrong with it.

After talking to Alienware I have found out that the 17 r5 has a slight glitch my system is trying to run the 2080 and the 1070 in SLI. I get lower fps with the 1070 enabled the r5 is designed to run with both cards the external for a external monitor only and  the internal for the laptop screen only. Its why I am able to turn the amp off and not have to shutdown my system  to turn it off. Only walk around so far is to go into device manger and disable the 1070 after startup to get benchmarks and games only use the 2080. long story short a new power supply for the amp made the amp stop making a squealing noise . and all is good now just have to disable the 1070 every time. 

I had a 17 R4 and the graphics amp worked great. I then got a 15 R4 as a work laptop, if connected the laptop to the graphics amp and it corrupted the graphics drivers I assume and the system wouldn't boot. I restored it using an image I took, tried again, same thing. I had to return that machine because of other issues it was having, and replaced it with a 17 R5. This time after I booted, it couldn't see drivers for the 1080Ti in my amp or the built in 1070. Tried to install the drivers, this time it wouldn't output to my external display and the HDMI port wasn't sending out a signal. So disapointed by all of this. I don't think I will be buying any more alienware devices after this.