Intel Core i7-5775C Broadwell Processor Assessment

Last month we got our first glimpse of the new "Braswell" system-on-chip solutions from Intel in the form of the Pentium N3700 and the Celeron N3050B. These new SoCs used the 14nm process and had the new Airmont CPU cores from Intel. Braswell promised to be more efficient than the company's 22nm Silvermont microarchitecture – but what caught our attention was the vastly improved 3D performance.

Broadwell, like Braswell, is a 14 nm stump. Broadwell is a derivative of Haswell that was manufactured using the 22 nm process. The switch to a smaller process naturally leads to a smaller chip and lower power consumption. As is so often the case with Intel's "tick" updates, a few minor changes have been made.

Year of publication Microarchitecture Tick ​​or tock Process node
2015 Broadwell Tick 14nm
2013 Haswell Tock 22nm
2012 Ivy bridge Tick 22nm
2011 Sandy Bridge Tock 32nm
2010 Westmere Tick 32nm
2008 Nehalem Tock 45nm
2007 Penryn Tick 45nm
2006 Conroe Tock 65 nm

The advantage of this small update is that it is compatible with the existing LGA1150 platform, at least if an Intel 9 chipset is used. It is also possible that Z87 motherboards will support these new processors with a BIOS update.

Our Braswell test touched on the fact that setbacks in developing the 14nm process delayed the arrival of desktop Broadwell parts, especially the high-performance variants – although the Z97 board family supports Broadwell processors, the processors themselves were missing so far .

Intel officially announced ten new Broadwell processors on June 2, 2015 and was only distributing very limited test reports at the time – unfortunately we then missed them. However, we were a long way from being the only one, and it is still almost impossible to get our hands on the now long series of processors.

Our sources indicate availability in early August – which is strange since Broadwell was announced two months earlier. In addition, Broadwell has already been very delayed, so it is surprising that Intel has opted for an apparently unorganized soft start.

However, we now know that nearly a dozen desktop Broadwell CPUs are coming in, and today we have the flagship model on hand. Of the ten new models, five are 65W desktop processors and five are 47W laptop processors.

The new Broadwell processors

All five desktop Broadwell models are quad-core parts with integrated Iris Pro graphics from Intel and the associated Crystal Well L4 cache (more on that in a minute).

Of the five Broadwell 65W desktop processors, only two are LGA1150 socket parts – the rest are BGA chips that are soldered directly onto the circuit board. Unlike Haswell, both the LGA and BGA parts have the same integrated graphics engine.

i7-5775C i7-5775R i5-5675C i5-5675R i5-5575R
Fundamental frequency 3.3 GHz 3.3 GHz 3.1 GHz 3.1 GHz 2.8 GHz
Turbo frequency 3.7 GHz 3.8 GHz 3.6 GHz 3.6 GHz 3.3 GHz
Cores 4th 4th 4th 4th 4th
subjects 8th 8th 4th 4th 4th
graphic Iris Pro 6200 Iris Pro 6200 Iris Pro 6200 Iris Pro 6200 Iris Pro 6200
EUs 48 48 48 48 48
Graphics frequency 1150 MHz 1150 MHz 1100 MHz 1100 MHz 1050 MHz
DRAM frequency 1600 MHz 1600 MHz 1600 MHz 1600 MHz 1600 MHz
L3 cache 6 MB 6 MB 4 MB 4 MB 4 MB
L4 cache (eDRAM) 128 MB 128 MB 128 MB 128 MB 128 MB
interface LGA BGA LGA BGA BGA
Price $ 366 $ 348 $ 276 $ 265 $ 244

If we look at the Core i7-5775C that we have today and the BGA version (i7-5775R), both chips are almost identical. Apart from the fact that the Core i7-5775R is a BGA part, the only other difference is the turbo frequency, which is only 100 MHz higher at 3.8 GHz. Another difference is the price. While the Core i7-5775C offers a MSRP of $ 366, the 5775R costs a little less at $ 348.

The two desktop processors that our readers are likely to be most interested in are the Core i7-5775C and the Core i5-5675C. The Core i5-5675C is 25% cheaper, but does without HyperThreading support and reduces the number of threads from 8 to 4. The base frequency has also been reduced by 200 MHz, although only 100 MHz separate the turbo frequencies. Another big change is the amount of L3 cache, which has been reduced from 6 MB to 4 MB.

It's worth noting that the Haswell Core i7 parts have a larger 8MB L3 cache, while the Core i5 processor got a 6MB L3 cache. It's also worth noting that the Core i7-5775C and i5-5675C are both unlocked parts, although they don't have the traditional K designation.

It is particularly interesting that the massive L4 cache has its own code name – "Crystal Well". Crystal Well is a 128 MB eDRAM that was first used in Haswell processors with the Iris Pro Graphics 5200, mostly mobile processors.

The problem with all built-in graphics is bandwidth – they almost don't have enough of it. Imagine a discrete graphics card with an extremely low budget, such as the Radeon R7 250 with a memory bandwidth of 73.6 GB / s. In comparison, the Intel HD Graphics 4600 of the Core i7-4790K in conjunction with the DDR3-1600 memory offers a poor theoretical peak bandwidth of only 25.6 GB / s, which corresponds to about a third of the discrete card.

Since the eDRAM works on these Broadwell processors at 1.8 GHz, it offers them an additional bidirectional throughput of over 57 GB / s (114 GB / s in total). Even better, the large L4 cache is not only available for the graphics engine, the CPU can also access this cache. When using a discrete GPU, the eDRAM focuses on caching CPU requests, which effectively gives Broadwell desktop processors a massive 128MB L4 cache.

Together with the much faster eDRAM cache, Intel has expanded the Iris Pro 6200 (GT3e) graphics engine to 48 EUs at 1150 MHz, in contrast to the 20 EUs used by the HD Graphics 4600. This means that top gigaflops are now at 883 GFLOPS for the i7-5775C and 844 GFLOPS for the 5675C, as opposed to just 400 GFLOPS for the i7-4790K.

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