In our first part of our Broadwell coverage, we rushed to test both the i7-5775C and the i5-5765C in our new benchmarking suite against the previous generation of Haswell processors as well as AMDs Kaveri lineup. In Part 2, we have spent more time with the architecture to see how it stacks up against the last four years of Intel, as well as probing the high end overclocking capabilities.

Since our Part 1, the news mill from Intel has been an interesting mix of reduced revenue from the PC segments but a rise in expectation as we move from a dull Q2 into an exciting Q3 with back-to-school sales on the horizon and the release of Windows 10. Throw into the mix details about Intel's delayed 10nm process node, the injection of Kaby Lake processors after Skylake to break the tick tock model and it becomes an interesting next few years for the industry.

No matter the state of the tick-tock model (or what seems to be a tick-tock-tock with Kaby Lake), Intel's goals are still the same - improve efficiency of the main processor design and boost peak performance though instruction per clock (IPC) gains with each new processor design release. Simply stating you want an improvement in IPC and actually designing the semiconductor to get a boost in performance are two opposite ends of the difficulty spectrum.

Broadwell vs. Haswell

Intel's line of Haswell (4th generation) processors were released in June 2013, with a small updated design called Haswell Refresh in mid-2014 with improved frequencies and a small a package upgrade to benefit temperatures. Haswell is the name of the architecture, updating from the architecture on Ivy Bridge but on the same 22nm process node as Ivy Bridge. An architecture update incorporates a numerical of things - either a paradigm shift in the underlying semiconductor design, or a step up from the previous orientation by aiming for the low hanging fruit (times which can be updated for the most gain and the least effort). As a result, architecture jumps usually produce big (5-25%) jumps in performance. This is a tock, to use Intel's nomenclature.

Intel's Tick-Tock Cadence
Microarchitecture Process Node Tick or Tock Release Year
Conroe/Merom 65nm Tock 2006
Penryn 45nm Tick 2007
Nehalem 45nm Tock 2008
Westmere 32nm Tick 2010
Sandy Bridge 32nm Tock 2011
Ivy Bridge 22nm Tick 2012
Haswell 22nm Tock 2013
Broadwell 14nm Tick 2014
Skylake 14nm Tock 2015
Kaby Lake (link)? 14nm Tock 2016 ?

The other half of the equation is a tick, or the movement from a larger process node to a smaller process node. This is by and large a scaled reduction in the mask used for the processor, but there are potential benefits based on the die area of the components of the processor and the connections within. Moving down to a smaller node typically does not change the base hardware underneath, but optimizations are made based on that die area reduction. With this in mind, we typically see smaller benefits in performance (5-10%), but better improvements in power consumption due to smaller transistors needing less voltage (although this is a balance between higher leakage currents). Overall, the typical goal of a process node change is typically efficiency, making it favored in mobile platforms.

Moving from Haswell to Broadwell on the desktop is a process node change, migrating from 22nm on Haswell to 14nm on Broadwell. As a result, the first processors released under the Broadwell nomenclature were mobile focused (Core M), and the desktop end of the stack us the last one to be updated. Though the desktop side is more subtle than that - Intel has released mid-powered versions of the processor with high end integrated graphics, an approach normally reserved for mobile devices or integrated devices such as all-in-ones. Perhaps it is then unsurprising that when desktop processors are launched under the -S or -DT naming scheme, Broadwell on the desktop is part of the -H line, normally reserved for mobile processors.

We've commented on Broadwell's minor architecture adjustments over Haswell before. They focus on reducing cache misses and keeping more predicted operations in flight at any one time, reducing the need to move back out of memory and increase throughput. This is mostly achieved by exploiting the available area when function units are reduced in size from the node change - increasing the out-of-order scheduler size, increasing the L2 TLB to allow for both more local misses/larger memory jump requests, and the page miss handler doubles in size.

This, according to Intel, accounts for a 5% increase in IPC (instructions per clock) by focusing on reducing the wait time for data for the traditional CPU part of the Broadwell processor.

In our initial review of the Broadwell processors, we saw that it was not as straightforward as this. The two CPUs we tested, the i7-5775C and the i5-5675C, are built to a 65W thermal design power, compared to the high end models from Haswell which are at the 84/88W level. This means that for users looking for the next most powerful processor, the base processor frequencies of the Broadwell samples we had are lower and less performant due to frequency, more than any IPC increase could overcome.

Core i7-5775C lining up with the Core i7-4790K

It was difficult for Broadwell to win any CPU focused benchmark from a pure frequency (and TDP) handicap. To add an additional element into the mix, almost every Broadwell's memory cache system is also different:

Intel Desktop Processor Cache Comparison
  L1-D L1-I L2 L3 L4
Sandy Bridge i7 4 x 32 KB 4 x 32 KB 4 x 256 KB 8 MB  
Ivy Bridge i7 4 x 32 KB 4 x 32 KB 4 x 256 KB 8 MB  
Haswell i7 4 x 32 KB 4 x 32 KB 4 x 256 KB 8 MB  
Broadwell i7
(Desktop / Iris Pro 6200)
4 x 32 KB 4 x 32 KB 4 x 256 KB 6 MB 128 MB eDRAM

Haswell i5 4 x 32 KB 4 x 32 KB 4 x 256 KB 6 MB  
Broadwell i7
(i7-5700HQ / HD 5600)
4 x 32 KB 4 x 32 KB 4 x 256 KB 6 MB  

Both the Level 1 and Level 2 caches of each processor are the same, but at Level 3 where Haswell i7 has 8MB, the Broadwell i7 only has 6MB. Aside from the improved branch predictor mentioned above to reduce cache misses, Broadwell also has a separate eDRAM in the CPU package, weighing in at 128MB. This acts as a level 4 cache, having a latency between the L3 and moving out to memory, resulting in less trips out to main memory. This combination of architecture improvements and eDRAM on Broadwell combined with the lower L3 cache size makes it an unknown in memory performance.

I have also included the Haswell i5 and the Broadwell-based i7-5700HQ in this table, showing that the Broadwell i7 L1/L2/L3 cache hierarchy is more akin to a desktop i5 processor and that Broadwell is available without the eDRAM. That being said, the i7-5700HQ is a single processor destined for laptops, making any discrete testing nominally impossible, and taken out of the real-world context for the majority of Broadwell desktop owners.

The reason for Broadwell's eDRAM comes from Intel's ‘Crystal Well’ strategy. Crystal Well is a designation given to a processor which has this eDRAM (and typically a larger integrated graphics package as well). Integrated graphics are historically inhibited by memory bandwidth, having to almost always reach out to main memory to process textures in graphic workloads. The eDRAM allows more data to be stored between the graphics core and the memory, and at a higher memory bandwidth, potentially improving output. By combining the high end integrated graphics with the eDRAM, Intel created these Broadwell processors as the fastest integrated graphics solution available on a socketable (replaceable processor) platform.

That being said, due to Broadwell being the latest product from Intel, and it having the most recent (and expensive) process node, equipped with eDRAM which is a separate die on the package, the Broadwell solutions do not come cheap. The pricing is almost in line with previous Haswell mainstream i7 processors, albeit at the lower thermal design and the beefier integrated graphics. As we determined in the Broadwell Part 1 review, the desktop Broadwell has the absolute integrated performance crown, although an AMD APU system will be significantly more cost effective. Both platforms are hoping that multi-GPU possibilities in DirectX12 have a positive outcome to their solutions.

This Review

We said we'd be back for part 2, and this is it. Here I wanted to cover what we couldn't previously due to early BIOS revisions and limited time testing - specifically looking at how Broadwell performs when overclocking, and whether the Broadwell architecture is truly a step up over previous generations of Intel processors. In the last review our comparison point was the i7-4770K from Intel's Haswell line; for part two we also back tested the i7-3770K from the Ivy Bridge platform and the i7-2600K from Sandy Bridge, covering the four most recent Intel processor architectures dating back to January 2011. We also have data on older benchmarks going back further. All four of the most recent architectures are tested at their stock speeds and at a constant 3 GHz (at 1866 C9) to find how IPC improves. (Incidentally I did find an i7-750 and a Q9550 in my CPU bin for the next two generations back, but have no motherboards for testing our more recent benchmarks. I'll see what I can put together for a mini-piece later in the year.)

Test setup

Test Setup
Intel Core i7-5775C 65W 4C/8T 3.3 GHz / 3.7 GHz Broadwell
Intel Core i7-4770K 84W 4C/8T 3.5 GHz / 3.9 GHz Haswell
Intel Core i7-3770K 77W 4C/8T 3.5 GHz / 3.9 GHz Ivy Bridge
Intel Core i7-2600K 95W 4C/8T 3.4 GHz / 3.8 GHz Sandy Bridge
Motherboards MSI Z97A Gaming 6 (LGA1150)
ASRock Z77 OC Formula (LGA1155)
Cooling Cooler Master Nepton 140XL
Power Supply OCZ 1250W Gold ZX Series
Memory G.Skill RipjawsZ 4x4 GB DDR3-1866 9-11-11 Kit
Video Cards ASUS GTX 980 Strix 4GB
MSI GTX 770 Lightning 2GB (1150/1202 Boost)
ASUS R7 240 2GB
Hard Drive Crucial MX200 1TB
Optical Drive LG GH22NS50
Case Open Test Bed
Operating System Windows 7 64-bit SP1

Many thanks to

Thank you to AMD for providing us with the R9 290X 4GB GPUs.
Thank you to ASUS for providing us with GTX 980 Strix GPUs and the R7 240 DDR3 GPU.
Thank you to ASRock and ASUS for providing us with some IO testing kit.
Thank you to Cooler Master for providing us with Nepton 140XL CLCs.
Thank you to Corsair for providing us with an AX1200i PSU.
Thank you to Crucial for providing us with MX200 SSDs.
Thank you to G.Skill and Corsair for providing us with memory.
Thank you to MSI for providing us with the GTX 770 Lightning GPUs.
Thank you to OCZ for providing us with PSUs.
Thank you to Rosewill for providing us with PSUs and RK-9100 keyboards.

Overclocking Broadwell
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  • doggface - Tuesday, August 4, 2015 - link

    Can intel please bring out a processor that destroys Sandy Bridge so that I don't have to hear all the smug comments every time they release a processor. I am so bored by them. Cant we talk about something interesting, like why is crystal well such a big focus for them when apparently all anyone wants in the enthusiast bracket is raw power?
  • jrs77 - Tuesday, August 4, 2015 - link

    And now look at all the PC-users who don't play games, but use their PCs for doing actual work.

    No tests of professional graphics software like Photoshop, Premiere, etc. No tests of professional audio-software like Reason, CuBase, etc. No tests of professional 3d-software that actually would benefit from the IrisPro and it's GPGPU-capabilities - and no, Cinebench is only for CPU-based rendering, so it doesn't count that much for stuff like flowsimulations done in Solidworks etc.

    The i7-5775C is currently the best CPU outthere for small workstations, due to the very powerful IrisPro and the low TDP. You can build a very powerful rig in a box as small as the MacMini while still keeping the advantage of the 4C/8T CPU and an iGPU as powerful as a R7-250/GT740.
    And this rig would only draw some 150W under full load, which is totally doable with a picoPSU.

    I'm getting my i7-5775C finally delivered sometime next week, after waiting for 2 month, and I can finally build the rig I've allways wanted to combined with the following: Antec ISK110, picoPSU 160XT, Noctua NH-L9i, 2x SSD (256/512 GB) and 16GB DDR3.
    Strapped to the back of my screen, allmost inaudible and very low power-draw.

    This CPU is ment for SFF-workstations, but for this niche it's the best there is.
  • MrSpadge - Tuesday, August 4, 2015 - link

    Thanks for the detailed review, Ian! As far as I know it's the most detailed out yet. And probably the last one, with Skylake hopefully just around the corner.

    Anyway, I would really like to see how low the power consumption of this chip can go. It's obviously optimized for mobile and low clocks, so pushing it to high clocks and high voltages (even the stock voltage is a lot for 14 nm!) is not showing it in its best light. When you tested the voltage scaling I would really like to see the minimum voltage needed to get to the lower speeds (you just left it at stock). How low can the power consumption of this chip become at ~1.0 V? Which clock speed hit does it take to get there? (btw: I run my 3770K at 4.0 GHz and a bit over 1.0 V, which is great for 24/7 load)
  • zlandar - Tuesday, August 4, 2015 - link

    No reason to replace my 4 year-old i7-2600k for gaming. Kinda nutty since I just installed my 3rd video card on the same system.
  • joanwa - Tuesday, August 4, 2015 - link

    Concerning the Linux Performance, could one kindly ask for another software to be benchmarked? NAMD is nice, but the to my knowledge the bigger share of the scientific community in molecular dynamics uses Gromacs (, which is also much faster and better optimized for current Hardware (AVX2 support for instance, multiple GPU support) and has a bigger community around it.
  • Morg72 - Tuesday, August 4, 2015 - link

    I'm still rockin' an i7-950, ASUS P6X58D-E, 12gb DDR3 1600 and 2x 6870's in Crossfire. The only part showing me its age is the 6870's (probably going to upgrade next GPU gen). The rest runs everything I throw at it perfectly and that's at stock speed. I can always get a better CPU cooler and OC it for more longevity. Intel really needs to get things together. Hope Zen gives them a push.
  • nagi603 - Wednesday, August 5, 2015 - link

    4770k owner here... If this is how Intel upgrades, I won't be changing this baby out for a decade.
  • Lazn_W - Wednesday, August 5, 2015 - link

    My question is: Does the L4 cache help with multi threaded use? Say a home Hyper-V server lab environment? It might make the 5775C a better buy than one of the hex core 2111 socket CPUs..
  • Jetpil0t - Thursday, August 6, 2015 - link

    They should put out a multi-threaded K series 4 core with no IGP at a basement price for the more value minded people, gamers specifically, especially considering the main purpose of upgrading are the tertiary features on the motherboard. I doubt anyone with a Sandy is looking at this with any interest. Especially considering my Sandy board has PCIe3.0 and Sata 6Gbps and rocks 4-4.5 Ghz easily.
  • SanX - Friday, August 7, 2015 - link

    Big fart of Intel.
    Remember AMD Bulldozer?
    Heads will be rolling.

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