NanoPi NEO4 is currently the smallest RK3399 board around. I got 2 pre-release samples provided by FriendlyELEC for tests, development and review. In the following I focus on things I'm interested in (that's headless server mode and nothing else)
As usual comprehensive information available in FriendlyELEC's wiki.
Quick summary:
- PCB size 60x45 mm (same form factor as NanoPi NEO Plus2 -- maybe we see more boards with this form factor from FriendlyELEC in the future)
- RK3399 ARM SoC capable of running the big cores at 2.0GHz and the little ones at 1.5 GHz (two challenges here: providing sufficient power and heat dissipation)
- 1 GB DRAM in dual-channel config (one 4Gb chip on each PCB side)
- Gigabit Ethernet using the usual RTL8211E PHY capable of 940 Mbits/sec in both directions
- Ampak AP6212 providing 2.4GHz wireless (single antenna/single band 802.11n Wi-Fi and BT 4.0)
- USB3 SuperSpeed available on the lower type A receptacle
- USB2 Hi-Speed available on 2.54mm pin header and the upper type A receptacle (my prototypes show both as blue but AFAIK this will be fixed with the final version)
- USB2 OTG on the USB-C port to enter Rockchip's Maskrom mode
- Powering via USB Type-C or Pin2&Pin4 of the 40-pin GPIO1 header (5V/3A recommendation by FriendlyELEC -- my personal recommendation is to always buy their 5V/4A PSU as well for reasons below)
- HDMI 2.0a, supports 4K@60Hz，HDCP 1.4/2.2 (only audio output asides the 8-pin I2S header)
- 1 x MIPI CSI input
- eMMC socket compatible to the other more recent FriendlyELEC boards
- 40 pin 1.27mm pitch SMD connector with PCIe Gen2 x2 and various GPIOs
Unlike other board makers FriendlyELEC tries to address different use cases with different boards being as compatible to each other as possible. NanoPC-T4, NanoPi M4 and NanoPi NEO4 share majority of hardware details (see rk3399-nanopi4-common.dtsi) and the differences can be spotted by comparing their individual device-tree (DT) files:
- NanoPC-T4 only defining the
modelname, - NanoPi M4 defining some eMMC and Audio stuff differently and
- NanoPi NEO4 defining another Wi-Fi chip (please note that at the time of this writing a wrong chip is referenced there since in the meantime it's a AP6212 Wi-Fi/BT combo).
So asides the different physical dimensions all three RK3399 devices from FriendlyELEC can run basically with the same OS images and need only minor adjustments (exchanged DT bits). The other differences are how PCIe lanes are exposed (M.2 key M with all 4 lanes available on NanoPC-T4, only 2 lanes on pin headers on M4 and NEO4) and how powering looks like.
While NanoPC-T4 utilizes a 5.5/2.1mm barrel plug to be fed with 12V both NanoPi M4 and NEO4 want to be powered with 5V via USB-C (or pin header).
Please be aware that the USB-C implementation is not USB PD compliant (USB PD --> USB power delivery specification) and is just a 'dumb' 5V DC input. This has both advantages and disadvantages.
Pro: No need for a true USB PD compliant USB-C charger (those that do not set your equipment on fire are pretty expensive)
Cons:
- you'll also need a 'dumb' 5V PSU since 'real' USB-C chargers won't negotiate a current high enough (same problem with NanoPi M4)
- Low voltages and high currents are not a great combination since cable and contact resistance become a problem leading to severe voltage drops (same problem with NanoPi M4). So if you plan on attaching USB consumers or run demanding workloads take care that the USB-C cable you use to power the board is short and of highest quality (low AWG rating to prevent voltage dropping)
My personal recommendation is to also aquire FriendlyELEC's 5V/4A PSU that ships with a very short USB-A to USB-C cable (picture) if you plan to connect board powered USB peripherals like SSDs or 2.5" HDD. In any case please ensure you take the voltage drop issue into account and always use a very short USB-C cable with thick power wires to provide power.
I did only a quick test with a powermeter connected to mains (Brennenstuhl Primera Line PM 231E bought after german c't magazine reviewed it as one of the more precise powermeters available). With FriendlyELEC's 5V/4A PSU my 231E reports 0.3W without any load connected. When feeding NEO4 it reports 2.7W in idle.
For further numbers please compare with NanoPi M4 review in Armbian forum keeping in mind that there the watts reported are measured between board and PSU so absolute numbers aren't comparable (every PSU wastes some energy on its own). But relative consumption differences will be identical between both boards since it's RK3399 after all.
As expected the RK3399 here performs like any other RK3399 on this planet. The only interesting questions are how heat dissipation works here (RK3399 since somewhat beefy will overheat and needs to be throttled without sufficient heat dissipation) and how memory implementation looks like.
I added NEO4 performance numbers already to sbc-bench results. For reasons unknown yet when running NEO4 with appropriate DT (rk3399-nanopi4-rev04.dts) memory bandwidth and especially latency is slightly worse compared to running with NanoPi M4 settings (but doesn't matter with almost all use cases)
So let's look at heat dissipation now:
FriendlyELEC provides a massive milled Aluminium heatsink for the board that ships with a 20x20x1.5 mm thermal pad to connect heatsink with RK3399. Unfortunately these thermal pads perform rather poorly wrt heat transfer (see NanoPi Fire3, NanoPi K1 Plus, NanoPi M4 and RockPro64) so my personal recommendation is to replace the vendor provided thermal pad with a 1.2mm copper shim and two thin films of thermal compound.
I had a detailed look at heatsink efficiency here but regardless whether you use the thermal pad or exchange it with something working better there are three simple rules:
- You need a heatsink unless NEO4 should idle all the time. Usually the PCB acts as an own heatsink but here PCB size is that tiny that you can't rely on.
- If your use case involves only short peak loads then FriendlyELEC's massive heatsink does the job (the huge Alu block can compensate easily for short SoC temperature increases)
- If you plan on continous full load you need an additional fan or at least some sorts of airflow through the heatsink fins. The thermal mass of FE's heatsink is quite large so after some time the heatsink itself will store the heat mostly and you end up with an overheated board
We have 5 different types of storage capabilities here: SD card, eMMC, USB2 attached storage, USB3 attached storage and (potentially) PCIe attached storage.
Let's look at them individually:
SDR104 mode and switching from 3.3V to 1.8V is supported so we get up to 68 MB/s sequential transfer speeds and nice high random IO performance with appropriate SD cards.
Quick check with an A1 rated SanDisk Extreme card (using my standard iozone test)
SanDisk Extreme A1 random random
kB reclen write rewrite read reread read write
102400 4 3672 3640 12849 12881 9463 3175
102400 16 10923 11322 28427 26624 27124 7938
102400 512 55800 60169 63952 64218 64191 58994
102400 1024 62335 62258 66023 65997 65962 60514
102400 16384 63758 63970 67797 67798 67744 63299
With RK3399 up to 300 MB/s sequential transfer speeds are possible but actual storage performance of course depends on the eMMC module used. See my ODROID-N1 review and there especially Hardkernel's Samsung eMMC 5.1 numbers with varying capacity. Numbers for FriendlyELEC's 8GB SanDisk eMMC module made with M4 (will be the same on NEO4 since RK3399 is RK3399):
8GB FriendlyELEC SanDisk eMMC random random
kB reclen write rewrite read reread read write
102400 4 8565 8793 24853 24808 19463 8523
102400 16 25604 25986 66627 66701 56571 24459
102400 512 42217 42326 125788 126508 125959 40394
102400 1024 42762 43178 129692 129726 130452 42636
102400 16384 43914 42877 132828 133254 133417 43012
RK3399's USB2 implementation supports the modern USB Attached SCSI (UAS) protocol but for whatever reasons sequential transfer speeds are limited to 35 MB/s. Test with my usual EVO840 test SSD in my usual JMS567 disk enclosure (to keep numbers comparable)
Samsung EVO840 USB2 random random
kB reclen write rewrite read reread read write
102400 4 8251 10611 8310 8386 8315 10549
102400 16 20995 21068 21609 21695 21775 21180
102400 512 32767 32832 33033 33251 33124 32914
102400 1024 33508 33498 34003 34115 34148 33558
102400 16384 34162 34106 34994 35057 35137 34181
The USB3 port is also UAS capable and the storage performance is excellent exceeding 400 MB/s (additional numbers for the same SSD provided with a VIA VL716/VL715 bridge since interestingly while sequential top speeds are lower especially random IO performance with small block sizes is way better -- and that's important with fast SSDs and not sequential performance):
Samsung EVO840 USB3 / JMS567 random random
kB reclen write rewrite read reread read write
102400 4 28357 31510 25159 25175 25144 31057
102400 16 92856 100504 86410 86688 86502 98909
102400 512 326427 333811 302924 305825 305952 328410
102400 1024 356554 365881 340886 342295 344505 360279
102400 16384 383442 387693 390023 394239 393870 378899
2048000 16384 402752 405067 395700 396042 396023 404387
Samsung EVO840 USB3 / VL716 random random
kB reclen write rewrite read reread read write
102400 4 35816 40837 26554 26585 26502 40387
102400 16 107127 119194 89773 90055 90052 115743
102400 512 300228 307147 292255 296349 296201 302348
102400 1024 324002 338868 327037 330841 331600 327289
102400 16384 370782 370772 376650 380148 380017 372915
2048000 16384 380944 382969 380036 380358 380308 383308
Not able to test now since PCIe on NEO4 is only available on the 40 pin 1.27mm pitch SMD connector. I really hope FriendlyELEC or 3rd parties provide an ASM1062 'SATA HAT' for this connector as already suggested. This would allow to power NEO4 and up to two 3.5" HDDs reliably with 12V while providing 2 SATA 3.0 ports that are even fine with 2 SSDs behind (ASM1062 would utilize both PCIe lanes)
Gigabit Ethernet as usual with RK3399 is saturating the link (940 Mbits/sec in both directions) and since Wi-Fi is 2.4 GHz only and AP6212 numbers have already been generated it's not worth the efforts to measure (reasons why). Please keep in mind that with current software support situation neither Wi-Fi nor BT will work right now. DT modifications, driver activation and further tweaks are needed.
There's 1 x USB3, 2 x USB2 (one time on a pin header), the USB OTG port is routed to the USB-C connector (not using the SuperSpeed data lines so you're limited to USB2/Hi-Speed here).
Two PCIe Gen2 lanes are routed to the 40-pin header but since this connector is proprietary it needs specially designed 'HATs' or PCIe expanders to make use of them (and I really hope we'll see some of them since this is still an amazing feature for such a tiny board to expose this universal high speed bus in that way!)
On the 40-pin header a few more protocols are exposed (please check FriendlyELEC's wiki for details)
None yet except this thing being the perfect pocket server once an enclosure ready for the massive heatsink is available (I could imagine something 3D printed with the heatsink completetly being outside of the enclosure)