Moorefield in the house
The Venue's Atom Z3580 processor provides our first glimpse of Intel's Moorefield SoC. This chip is fabbed on the same 22-nm, tri-gate process as the Bay Trail silicon found in budget Android tablets. But it's designed to fit into smartphones, so the thermal envelope should be tighter than Bay Trail's 2W SDP. (SDP refers to Scenario Design Power, a thermal rating meant to be more relevant to real-world workloads than traditional TDP ratings.) Surprisingly, the Z3580's official specifications lack details on the thermal envelope. We've asked Intel for clarification.
Moorefield is based on the same Silvermont CPU architecture as Bay Trail. All the gory architectural details are explained in this article, but the big bullet points are support for 64-bit instructions and out-of-order execution. The other important item of note is the x86 instruction set, which differs from the ARM ISA that dominates the mobile world.
Intel and Google have been collaborating on x86 Android optimizations since 2011, so the ISA shouldn't pose a problem with modern software. Android's Dalvik VM can generate the appropriate instructions, and binaries compiled with the Native Developer Kit can target x86 specifically. In cases where ARM-specific code is the only option, binary translation software serves as an interpreter. There's some unavoidable overhead associated with translating ARM instructions to x86, but Intel contends that the impact is minimal. Any potential ISA issues may ultimately be rendered moot by Lollipop, which features a new runtime environment with a cross-platform compiler.
|Dell Venue 8 7000|
|SoC||Intel Atom Z3580|
|Manufacturing process||Intel 22 nm|
|CPU cores||4 Silvermont|
|Max core frequency||2.33GHz|
|System memory||2GB LPDDR3|
|Memory config||2 x 32-bit channels at 1600 MHz|
Silvermont uses a dual-core module with 1MB of L2 cache shared between the cores. There are two modules in Moorefield, giving the SoC four CPU cores and 2MB of total L2. The Z3580 is the fastest Moorefield variant in Intel's stable. It can scale up to 2.33GHz in Burst mode and down to a minimum frequency of just 333MHz. CPU-Z shows the chip regularly hitting top speed in the Venue 8 7000, and the frequency never drops below 500MHz when the app is running. Cores 0 and 1 run at the same speed, as do cores 2 and 3, which makes sense given the module-based arrangement.
Moorefield's integrated memory controller has dual 32-bit channels with support for LPDDR3 memory up to 1600 MT/s. The chip can handle 4GB of RAM, though only half that amount is deployed in the Venue. 2GB is probably sufficient for most folks, and I didn't encounter any situations where the tablet ran out of memory (that I could tell). Matching the memory capacity of cheaper slates like the Nexus 7 is hardly shooting for the stars, though. My OnePlus One smartphone has more RAM than the Venue—and it costs less, too.
Unlike Bay Trail, which features Intel's own GPU, Moorefield relies on PowerVR Series 6 graphics from Imagination Technologies. We'll delve into the GPU in a moment, so let's move on to a couple other items. Cellular connectivity isn't integrated into the SoC, but Moorefield is optimized for Intel's LTE modems. An LTE-equipped version of the Venue is reportedly on the way. A variant with USB 3.0 isn't in the cards, however. Although Moorefield supports the SuperSpeed spec, Dell deemed Gen2 connectivity to be sufficiently fast for the Venue—and easier to integrate into its slim chassis.
SoC and CPU performance
We've tested the Venue 8 7000 against several devices, the most comparable of which is Nvidia's Shield Tablet. The Shield is based on the quad-core version of Nvidia's Tegra K1 SoC. That chip uses off-the-shelf ARM cores rather than the custom Denver cores in the dual-core version of the Tegra K1 found in the Nexus 9. (We're still trying to get our hands on one of those for testing.) There are two sets of results for the Shield below: one with the latest Lollipop build and another from the initial KitKat config.
Other competitors of note include the Nexus 7 2013, which has a Qualcomm Snapdragon S4 Pro with quad Krait cores, and the Asus Memo Pad ME176C, a budget 7-incher powered by the Bay Trail-derived Atom Z3745. The Z3745 matches Moorefield's core count, but the CPU only scales up to 1.86GHz.
There are several smartphones and phablets in the mix, as well. These aren't in the same class as the Venue, but they can provide a helpful frame of reference for other SoCs and devices. The Apple A7 chip in the iPhone 5S, for example, is also used in the iPad Mini 3.
All the Apple devices have dual-core SoCs. The A7 uses Cyclone cores, the A8 in the iPhone 6 and 6 Plus features a tweaked version of Cyclone, and the A6 in the iPhone 5 is based on an older Swift CPU design. On the ARM front, the Korean version of the Galaxy Note 4 we tested sports a Samsung Exynos 5433 SoC that combines quad Cortex-A57 cores with quad A53s. The LG G3 and OnePlue One are both based on the Snapdragon 801, which has quad Krait cores.
One more thing. While the handsets operate within smaller power envelopes, the Venue is thinner than all of 'em. It just gets to dissipate heat over a much larger footprint.
The Venue 8 7000 falls well short of its peak theoretical memory bandwidth in this directed test. Dual 32-bit channels tied to 1600 MT/s memory should be good for about 10GB/s, but the tablet manages no better than 7.2GB/s.
Still, the Venue comes out looking pretty good versus the other tablets. It trades blows with the Shield in the single- and multi-threaded tests, and it scores higher than the Nexus 7 and Memo Pad in both of them.
Geekbench runs natively on both iOS and Android, and it offers us a look at both single- and multi-threaded performance. Click on the buttons below to toggle between the two sets of results.
The Venue 8 7000 mostly sticks to the middle of the tablet pack. It's slower than the Shield Tablet but faster than the Memo Pad and Nexus 7 through most of the single- and multi-threaded tests.
That said, the Venue stomps the Shield by a factor of five in the AES encryption test. The Memo Pad also fares well there, but its slower Bay Trail chip can't keep up with the Venue's faster Moorefield silicon. The Atom processors in both of those tablets support AES-NI instructions, a capability that Geekbench appears to exploit to great effect.
Broadening our focus to include handsets still leaves the Venue near the middle of the field. The tablet goes back and forth with the iPhone 6 and 6 Plus in the multi-threaded tests, but it can't keep up in the single-threaded ones. Meanwhile, the Galaxy Note 4 is faster across the board.
Here's a closer look at how the Venue's performance scales between one and many threads.
|Geekbench floating point||845||3044||3.6x|
|Geekbench AES encryption||396||1576||4.0x|
Performance increases by 4x in the encryption and raytrace tests, neatly living up to the potential of Moorefield's quad-core config. The scaling isn't perfect in the integer and floating-point tests, though, and it's barely more than 3x overall.
The Venue lands near the middle of the pack in most of our browser benchmarks. In SunSpider and Kraken, it's once again wedged between the Shield and other Android tablets. The latest iPhones are comfortably ahead, though.
Google's Octane benchmark apparently has a different makeup, because the Venue fares much better in that test. It's just a smidgen behind the leading iPhone and ahead of the Shield Tablet.
BaseMark OS II
Moorefield handles WebXprt with aplomb, posting the highest overall score and taking wins in two of four component tests. It only loses ground to the Shield Tablet in the offline notes test, and then only by a smidgen to the Lollipop config.
I'm a little surprised to see the Venue outpace the Memo Pad by such a large margin, especially in the face detection test. The Memo Pad is outfitted with just 1GB of RAM, a limitation that may contribute to slower performance in some tests. It can't even complete the Octane benchmark without the browser crashing.