Unsolved
This post is more than 5 years old
2 Posts
1
12712
Dell XPS 13" 8th-gen: what kind and how many PCIe lanes on M.2 ?
this is for someone from Dell to answer.
I just bought an 8th-gen Dell XPS 13". it has the Core i7-8550U and i ordered one with 16GB LPDDR3 1866MHz memory, 256gb PCIe SSD .
my question: for M.2 slot, how many PCIe lanes are available? are they PCIe 3.0?
i am wondering in case i decide to upgrade the SSD at a later time and I don't want to buy an SSD that is faster than the bandwidth available to the M.2 slot.
bonus question: what Intel chipset does the motherboard use?
thanks.
jphughan
4 Operator
4 Operator
•
14K Posts
0
October 2nd, 2017 16:00
If you already have this system, use a utility like HWInfo64 to expose the information you're looking for. The 9350 and 9360 both had 4-lane M.2 slots, and I'm fairly certain they were PCIe 3.0 since that's been around for a while now, so I imagine the new version will be the same -- in fact when I last checked Dell's site, even the version with an 8th gen Core CPU was being called a 9360. That said, that doesn't mean your SSDs will always perform at their max. I installed a Samsung 960 Evo into a friend's 9360 and I think it got something like 1.4 GB/s read, regardless of whether I used the native Microsoft or Samsung NVMe driver (BIOS set to AHCI mode to bypass Intel RST). Reviews of the 960 Evo have indicated that they can reach around 3.1 GB/s reads in certain systems, although I found several other reviews with numbers closer to mine, so I don't consider my result anomalous. It's possible that having a U Series CPU (low-power) is creating a bottleneck at such high SSD speeds given that the reviews I saw with 3 GB/s+ read speeds were typically performed on desktops with a top-end K series CPU.
ejn63
1 Rookie
1 Rookie
•
87.5K Posts
1
October 2nd, 2017 17:00
This is a light refresh of the XPS 9360 - except for the CPU, it looks like everything else remains the same.
The eighth generation Intel CPUs are simply a block shot against the forthcoming AMD Ryzen mobile CPUs -- just as AMD offers more cores for less money in desktops, so it will in mobiles -- but the mobile market is more important to Intel -- so it is striking first before AMD does, rather than after (as it has done with desktop CPUs).
bigGG
2 Posts
1
October 4th, 2017 04:00
As far as I know both the 9350 and the 9360 with Kaby Lake 7th Gen have 4 PCIe lanes for the M.2. The problem why nobody can get more than 1.8 - 1.9 GBps is that the OPI (interconnection interface for the CPU) is set to GT2 which allows a max speed of 2 GBps and not to GT4 (max. 4 GBps). The most probable reason why Dell does that is that GT2 saves more power that GT4.
It would be wonderful if Dell would set a toggle in Bios so that the user can decide if he wants GT4 for performance or GT2 for power saving. :-)
jphughan
4 Operator
4 Operator
•
14K Posts
0
October 4th, 2017 09:00
I did not know that, but thank you for posting that info! I agree that would be a nice feature to have, especially if the hardware to support it is already there and this really is just a configuration item.
ejn63
1 Rookie
1 Rookie
•
87.5K Posts
0
October 4th, 2017 11:00
Allowing that option might just lead to SSD overheating in the cramped confines of an ultra-slim notebook.
SSDs consume a fair amount of power for their size - dissipated as heat -- there isn't room inside a slim notebook for a large enough heatsink to run the SSD flat out (gaming notebooks are much larger in size -- and have much better air flow).
I suspect the issue is to prevent the SSD overheating as much or more than it is to preserve battery life.
bigGG
2 Posts
0
October 5th, 2017 04:00
I absolutely agree that SSD's can consume a lot of power. But when they reach critical temperatures they don't really overheat, they just start throttling - exactly the same as the CPU.
In a slim Notebook like the XPS 13 they would eventually start throttling when the user moves big amounts of data. But not really under normal usage like, let's say, starting chrome with 3-4 windows and 50 tabs.
What I mean is that by setting the OPI to GT4 you wouldn't get much better results in long time benchmarks ( because of the throttling ) but you would get better responsiveness from the system.
Exactly in the same way as the CPU. It is almost impossible to hold the CPU turbo for a long time in a slim notebook but you don't need it most of the time. These few seconds that the CPU hits the turbo are in 99% of the time enough to give you a responsive notebook and a smile in your lips :-)
bkampsch
2 Posts
0
October 30th, 2017 12:00
I got my XPS 13" 8th gen with default 256gb SSD. I ran Crystal Disk Mark with default settings and get the following:
Seq Q32T1, read=1849 MB/s, write=1068 MB/s
4K Q32T1, read=395.8 MB/s, write=356.8 MB/s
Seq, read=1356 MB/s, write=361.9 MB/s
4K, read=47.27, write=120.9
Using ATTO again the fastest read I saw was ~1800 MB/s and the fastes write was just over 1050 MB/s.
hope this helps in case anyone is wondering what to expect!