Precision 7730,5530,7530 (Coffee Lake) pre-release

5520 - 2 lane
5530 - 4 lane

 

Important follow-up question, do these lanes come off of the CPU directly or off of the PCH? Ideal x16 for the 5530 would be x8 to dGPU, x4 to NVMe SSD, x4 to TB3 controller (in my opinion)

 

Well, don't forget WiFi (unless if the southbridge finally has it built in), since all of the decent cards (e.g. Intel) are PCIe-only.

 

It seems the mobile p2000 variant is significantly different with only 768 Cuda cores as opposed to 1024 and clock speed of 1557Mz down from 1752 MH.

 

Yeah, its specs look a lot like a slightly lower clocked GTX 1050Ti (mobile).

 

All of the mobile Quadro Pascal cards are downgrades from the same-named desktop cards. (Nothing new, this was true in the prior generation as well.)

 

WiFi is pretty much ALWAYS off the PCH as it only ever needs PCIe x1 so the flexible IO makes sense here. Additionally, with the 8 series chips, the WiFi MAC is built in and only an external PHY is required I believe (a la 9560). And thirdly, the extra latency of going over the DMI to the PCH is a non issue for something like (WiFi) network transfers as these are orders of magnitude slower than connections to a GPU or other high bandwidth PCIe attached devices (for 10 Gbps networking you WOULD want that on the CPU directly). The same is true of storage which is why pretty much all NVMe implementations actually happen through the PCH rather than come directly off the CPU. The added latency and bottleneck of the DMI is just not a real-world issue for that workload.

 

According to the two reviews, the 5520 is MIL-SPEC tested unlike it's XPS counterpart and it's also thicker by 4 mm at the thickest point.
I always thought the 5520 had the exact same body, just with different specs.

Thickness
https://www.google.com.au/search?q=...ome..69i57.10057j0j4&sourceid=chrome&ie=UTF-8

MIL-SPEC
https://www.laptopmag.com/reviews/laptops/dell-precision-5520

 

I am pretty sure they are the exact same laptops with with different GPUs installed and different BIOSes (and maybe a TPM). 4mm on a laptop of that size is HUGE and would be obvious. And as for the MIL-SPEC, that is just saying they paid to have it tested, odds are the XPS would also pass. The laptopmag link you provided even says they have the same chassis and body.

 

I assume the height difference is caused by different measurement methods. One is counting the rubber feets which should be in the range of 4mm and another one is only counting the height without the feets. The first method is of course the exact and right one in my eyes