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Intel Core i7-5775C review: The unwanted desktop Broadwell has one neat trick

Gordon Mah Ung | Aug. 4, 2015
The narrative is already in place on Intel's new Broadwell for desktop CPU: It's the chip no one wanted.

How we tested

For my test, I used an Asus Z97-Deluxe motherboard with 16GB of DDR3/1600 and 240GB SSD. I updated the motherboard to the latest UEFI available, installed a fresh copy of 64-bit Windows 8 and hunted down the latest drivers as well. Because the graphics capability of the the Broadwell C is a driving feature, I tested it without a discrete GPU.

I realize that decision doesn't track with what most people are doing with these expensive CPUs. I'd bet it's close to 90 percent who pair higher-end CPUs with graphics cards for gaming. Still, the graphics performance of these chips is a very important feature.

The competitor was a natural choice: Intel's Core i7-4790K, aka Devil's Canyon. 

The Core i7-4790K has a clock speed of 4GHz and will Turbo Boost up to 4.4GHz on some loads. It has Intel HD4600 graphics and on the street sells for $340. For more details, I've lined both them up at Intel's ARK website. It's pretty much the pinnacle of quad-core Haswell performance.

Besides the Broadwell to Haswell generation difference, the other factor that matters here is the clock speeds between the two chips. The Broadwell Core i7-5775C has a base clock of 3.3GHz with a Turbo Boost of 3.7GHz. 

Encoding

The first test we can discuss is our Handbrake workload. We use the free and popular Handbrake encoder to convert a massive 30GB MKV file into a much more compact MP4 file using the Android Tablet preset.

Notes: Our normal system review benchmark uses the 0.9.9 version but for this, I wanted to use the latest version of Handbrake 0.10.2. Because it does effect the encoding time, you can't compare results between the versions. Handbrake allows you to choose different encoders so for the first one, I used x264, which is heavily multi-threaded and keeps the workload to the x86 cores in the CPU.

The result was a big win for the Core i7-4790K and clock speed in general. 

But wait, encoding video isn't done just on the x86 side anymore. Today, encoding on the GPU is the way to go for performance, and Intel has dedicated transistors for hardware encoding into its chips, called Quick Sync. What happens when we give Handbrake the same task, but using the graphics cores instead?

Boom: The improved Broadwell graphics cores combined with its massive eDRAM flips this battle on its back. Besides whistling at how much of a recovery the Core i7-5775C made here, you should also take note of the encoding time it took using the GPU cores rather than the x86 cores in the CPUs. The Core i7-5775C, for instance, takes a third of the time to get the work done. There are arguments that GPU encoding leads to visual impurities, but when you're crunching a file down to watch on your phone, who cares?

 

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