I’m not using the M.2 E key slot for WiFi/bluetooth so I’ve ordered the following adapter: https://www.amazon.co.uk/KALEA-INFORMATIQUE-©-PCIe-Adapter-cable/dp/B078883MK2
This gives: PCI-e 1x slot and an internal USB 2 port
It is kind of cursed but I hope it is going to work 
At least according to the schematic, both the USB pins and the PCI-E ones are connected.
1 Like
NGFF M.2 Key M to Key A+E Extension Cable NGFF Adapter Card Converter For Windows 2000/7/8/10|Computer Cables & Connectors| - AliExpress is an adpater that allows you to add a second NVMe drive. Only the shortest of the provided cables worked for me.
1 Like
That seems interesting as well!
The length of the cable of the one I bought does worry me. I didn’t know PCI-e signal could span that long. But we’ll see. It’ll arrive today, just need to find a PCE-e 1x card to test with.
The clock speeds have increased from PCIe 1.1 (supported by the adapter on Amazon) to PCIe 3. This reduces the allowable cable length. With PCIe 4 cable length became so critical that motherboards even have repeaters to condition the signals to PCIe slots. I found these maximum cable lengths in the internet but I don’t know if they are reliable:
- PCIe Gen 1: 15 inches.
- PCIe Gen 2: 12 inches.
- PCIe Gen 3: 8 inches.
1 Like
Okay, thank you! That doesn’t bode well. I didn’t know about the differences between generations. Unmatched has “M.2 E-Key Slot (PCIe Gen 3 x1)”. The cable length of the adapter is 20cm, ~7.9 inch. Combined with the electronic specifications being way off…
Anyhow, I started looking for this because I needed an internal USB port (I’ve grossly wired one the long way around via the back now), so if that works it’s something .
This worked! I mounted the module, managed to find a molex-to-floppy(!) connector to power it, and the USB port works.
I’d also ordered a cheap-ish PCI-e card (1x gen-2 PCI-e to 2x USB3 19-pin connectors—could unfortunately find nothing that goes back to gen-1) but it had some delivery issues, so not able to check yet if it works out. If it does, I can have all front-panel USB ports working.
Hahahaha in Shelley’s name it actually works
mara@loreley:~$ lspci
00:00.0 PCI bridge: SiFive, Inc. FU740-C000 RISC-V SoC PCI Express x8 to AXI4 Bridge
01:00.0 PCI bridge: ASMedia Technology Inc. ASM2824 PCIe Gen3 Packet Switch (rev 01)
02:00.0 PCI bridge: ASMedia Technology Inc. ASM2824 PCIe Gen3 Packet Switch (rev 01)
02:02.0 PCI bridge: ASMedia Technology Inc. ASM2824 PCIe Gen3 Packet Switch (rev 01)
02:03.0 PCI bridge: ASMedia Technology Inc. ASM2824 PCIe Gen3 Packet Switch (rev 01)
02:04.0 PCI bridge: ASMedia Technology Inc. ASM2824 PCIe Gen3 Packet Switch (rev 01)
02:08.0 PCI bridge: ASMedia Technology Inc. ASM2824 PCIe Gen3 Packet Switch (rev 01)
04:00.0 USB controller: ASMedia Technology Inc. ASM1042A USB 3.0 Host Controller
05:00.0 USB controller: VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller (rev 01)
06:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981/PM983
07:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Lexa PRO [Radeon 540/540X/550/550X / RX 540X/550/550X] (rev c7)
07:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Baffin HDMI/DP Audio [Radeon RX 550 640SP / RX 560/560X]
mara@loreley:~$ lsusb
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 003: ID 24ae:1000 Shenzhen Rapoo Technology Co., Ltd. Rapoo 2.4G Wireless Touch Desktop
Bus 003 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 174c:3074 ASMedia Technology Inc. ASM1074 SuperSpeed hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 0403:6010 Future Technology Devices International, Ltd FT2232C/D/H Dual UART/FIFO IC
Bus 001 Device 002: ID 174c:2074 ASMedia Technology Inc. ASM1074 High-Speed hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Tried connecting devices and it looks like it picks them up too. Might try a USB3 disk later and do some performance tests.
I benchmarked performance with this external USB3 harddisk:
Bus 002 Device 003: ID 8564:7000 Transcend Information, Inc. StoreJet 25H3
Both the USB port of the motherboard as the PCI-e one detect it as SuperSpeed successfully. The performance difference is interesting though!
Tested with:
fio --name TEST --eta-newline=5s --filename=/dev/sda --direct=1 --rw=read --bs=64k --ioengine=libaio --iodepth=64 --runtime=120 --numjobs=4 --group_reporting --readonly
Output for PCI-e USB3 adapter connected through M.2 adapter (VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller):
TEST: (groupid=0, jobs=4): err= 0: pid=1487: Mon Sep 13 15:23:05 2021
read: IOPS=3517, BW=220MiB/s (230MB/s)(25.8GiB/120011msec)
slat (usec): min=20, max=178392, avg=1122.59, stdev=4427.52
clat (usec): min=931, max=257180, avg=71546.86, stdev=17858.04
lat (msec): min=10, max=261, avg=72.67, stdev=17.58
clat percentiles (msec):
| 1.00th=[ 51], 5.00th=[ 52], 10.00th=[ 67], 20.00th=[ 67],
| 30.00th=[ 67], 40.00th=[ 68], 50.00th=[ 68], 60.00th=[ 68],
| 70.00th=[ 68], 80.00th=[ 69], 90.00th=[ 71], 95.00th=[ 125],
| 99.00th=[ 142], 99.50th=[ 146], 99.90th=[ 224], 99.95th=[ 228],
| 99.99th=[ 257]
bw ( KiB/s): min=82560, max=246252, per=99.99%, avg=225075.11, stdev=9666.10, samples=956
iops : min= 1290, max= 3844, avg=3515.61, stdev=151.01, samples=956
lat (usec) : 1000=0.01%
lat (msec) : 2=0.01%, 10=0.01%, 20=0.01%, 50=0.08%, 100=92.80%
lat (msec) : 250=7.10%, 500=0.01%
cpu : usr=1.41%, sys=2.72%, ctx=34982, majf=0, minf=4217
IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=99.9%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, >=64=0.0%
issued rwts: total=422095,0,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=64
Run status group 0 (all jobs):
READ: bw=220MiB/s (230MB/s), 220MiB/s-220MiB/s (230MB/s-230MB/s), io=25.8GiB (27.7GB), run=120011-120011msec
Disk stats (read/write):
sda: ios=26352/0, merge=395075/0, ticks=237462/0, in_queue=237462, util=100.00%
Output for motherboard USB3 (ASMedia Technology Inc. ASM1042A USB 3.0 Host Controller):
TEST: (groupid=0, jobs=4): err= 0: pid=1516: Mon Sep 13 15:25:57 2021
read: IOPS=1543, BW=96.5MiB/s (101MB/s)(11.3GiB/120009msec)
slat (usec): min=19, max=64930, avg=2570.95, stdev=4445.08
clat (usec): min=1723, max=260436, avg=163095.64, stdev=10032.08
lat (msec): min=9, max=260, avg=165.67, stdev= 9.11
clat percentiles (msec):
| 1.00th=[ 150], 5.00th=[ 153], 10.00th=[ 153], 20.00th=[ 157],
| 30.00th=[ 161], 40.00th=[ 161], 50.00th=[ 163], 60.00th=[ 165],
| 70.00th=[ 165], 80.00th=[ 167], 90.00th=[ 169], 95.00th=[ 176],
| 99.00th=[ 209], 99.50th=[ 213], 99.90th=[ 251], 99.95th=[ 262],
| 99.99th=[ 262]
bw ( KiB/s): min=50688, max=102604, per=99.91%, avg=98705.18, stdev=1243.71, samples=956
iops : min= 792, max= 1600, avg=1541.58, stdev=19.43, samples=956
lat (msec) : 2=0.01%, 4=0.01%, 10=0.01%, 20=0.01%, 50=0.02%
lat (msec) : 100=0.04%, 250=99.81%, 500=0.11%
cpu : usr=1.04%, sys=1.53%, ctx=47009, majf=0, minf=4227
IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=99.9%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, >=64=0.0%
issued rwts: total=185245,0,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=64
Run status group 0 (all jobs):
READ: bw=96.5MiB/s (101MB/s), 96.5MiB/s-96.5MiB/s (101MB/s-101MB/s), io=11.3GiB (12.1GB), run=120009-120009msec
Disk stats (read/write):
sda: ios=46242/0, merge=138725/0, ticks=236833/0, in_queue=236833, util=100.00%
So despite the Frankenstein-contraption it (at least read throughput) manages to be more than twice as fast.