Raspberry Pi 3 Model B+
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The latest Pi’s SoC is 200MHz quicker than the Pi 3, and it also runs cooler.
Raspberry Pi 3 Model B+
Let’s start with a clarification: the Raspberry Pi 3 Model B+ isn’t a Raspberry Pi 4, which is now unlikely to appear before 2019. The core of the Pi 3 B+ is the same Broadcom BCM2837 processor that powers the Pi 3, although you’d be forgiven for not recognising it, thanks to a design overhaul, which sees the plastic chip package ditched in favour of a more desktop-like, silicon-die-underheatspreader approach.
That shift in design, which gives the
BCM2837 its B0 suffix, is responsible for two key advantages. The first is that, along with a new custom-designed power management integrated circuit (PMIC), which provides more accurate and stable voltage regulation while considerably simplifying the circuitry, the Pi 3
B+ runs at 1.4GHz to the Pi 3’s 1.2GHz. The second, more important, advantage is that the BCM2837B0 is now significantly more efficient at ridding itself of heat.
A comparative look at the two boards under the thermal camera tells the full story. After a ten-minute, all-cores benchmark run, the processor cores show up clear as day on the Pi 3 as 100°C hotspots on the plastic package, while the relatively thin PCB heats up only on one side. The Pi 3 B+’s new packaging, improved bonding and thicker PCB – resulting in a weight gain from 40g to 50g – dispense with these hotspots, keeping the package temperature well below fingertip-burning levels, and bleeding off the heat from the entire PCB.
That has two further impacts, which are less immediately obvious. The first is that, thanks to the heat now being spread more
evenly throughout the die, the on-board temperature sensor now reports the systemon-chip (SoC) temperature more accurately. Comparatively, the Pi 3 could hit over 100°C externally while reporting a sub-80°C internal temperature. The second is that thermal throttling is now more accurate and stable.
In real-world terms, this all translates into measurable gains in burst and sustained
performance. The Pi 3 B+ is the fastest Raspberry Pi I’ve tested by some margin – though far from the fastest single-board computer overall. A SysBench CPU test shows a 30.04-second completion time in four-thread mode, to the Pi 3’s 34.97 seconds and the Pi 2’s 54.55 seconds.
Meanwhile, memory benchmarks hit 857.96MB/sec read and 632.26MB/sec write, compared to the Pi 3’s 719.76MB/sec and 547.9MB/sec respectively.
It’s the networking side, though, where the biggest advantages can be found. For the first time, the Raspberry Pi is now available with a Gigabit Ethernet connection. Sadly, however, it’s still hamstrung by a shared USB 2 channel to the SoC. In real-world terms, this setup results in a ‘Gigabit’ connection that maxes out around the 212.9Mb/sec mark, a disappointment for all but the folks who have struggled with the 89Mb/sec peak of the older models. There’s even support for Power over Ethernet (PoE), although it requires the purchase of an optional add-on HAT.
Wi-Fi, too, is improved. The chip antenna of the Pi 3 has been ditched in favour of the same ground-plane antenna design used for
the Pi Zero W, and it offers a slight but reliable improvement in signal quality. The radio itself now supports both 2.4GHz and 5GHz operation, a first for the Raspberry Pi family, and it’s received an upgrade to Bluetooth 4.2 as well as the latest Bluetooth Low Energy (BLE) specification.
Perhaps the what’s most significant about the Pi 3 B+, though, is how little has changed. The board layout, bar the new PoE header, matches its predecessors exactly, and is
compatible with all accessories. On the software front, it’s still possible to burn the latest Raspbian operating system to a microSD card and insert it into any Pi, from the original launch model with its single-core BCM2835 and 256MB of RAM, right up to the new Pi 3, and have it operate perfectly.
Sadly, that also means many of the issues with the standard Pi design are still present: the 3.5mm AV jack’s quality is still poor, there’s that single USB 2 channel to the SoC for the Ethernet and USB ports, no 4K video support, just 1GB of RAM and no high-speed connections for peripherals.
That said, when this board has an asking price of just £32 inc VAT from suppliers, including https://shop.pimoroni.com (but not including a few unnamed chancers who hiked the price as high as £36), these issues pale into insignificance.
The Raspberry Pi family remains the bestsupported pocket-money microcomputer family, and the Pi 3 B+ is a worthy successor to the rather flawed Pi 3 design.
The Raspberry Pi 3 Model B+ isn’t a Pi 4, but it’s still a worthy upgrade from the Pi 3
A new, smarter PMIC chip means a simplification to the board layout and a reduction in the overall component count
A Power-over-Ethernet (PoE) header is a welcome addition, but needs add-on hardware to operate
Thermal imaging shows the significant impact of the new design on heat dissipation
The new Ethernet and USB controller provides a Gigabit Ethernet connection, but sadly not Gigabit throughputs
New packaging and bonding has improved the thermal characteristics of the BCM2837 SoC considerably