Intel Core i7-5775C: Broadwell for Desktops

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Energy Efficiency

Running off integrated graphics, the i7-5775C is on par with Haswell chips when it comes to power consumption during light load, shaving a couple of watts off at idle, but using a similar amount rendering Flash and H.264 video.

The i7-5775C has a slight efficiency advantage compared to the i5-4670K and i7-4770K on heavy CPU load but keep in mind it runs at a lower clock speed (3.7 GHz with Turbo Boost). However when its turbo-charged integrated graphics is put to the test in Crysis, the system pulls over 100W AC, substantially more than lower tier Haswell solutions.

The Prime95 stress test brings the chip close to its power limit as adding FurMark to the mix only results in a 1W increase. The 65W TDP seems to prevent either the CPU or GPU from its full potential depending on which is in greater demand. Raising the power limits in the BIOS allows the CPU to hit higher multipliers but when the GPU is stressed as well, the power draw still will not exceed 107W. The power consumption difference between Prime95 and Prime95 + FurMark when the CPU set to its minimum 800 MHz is 54W, so the system could theoretically pull ~160W if not constrained by the TDP.

The implication is that the CPU clock speed will throttle down during GPU-intensive tasks to abide the power limit. I can confirm this as the CPU clock speed was observed running between below 2.0 GHz during our gaming tests (the Haswell processors run at full speed). Thankfully this doesn't affect any of our gaming benchmarks as they are primarily GPU-dependent. With CPU-limited titles, you should expect a performance penalty.

Gaming Performance

Our real world gaming tests is conducted at two resolutions, 1366x768 and 1600x900 (or whatever is the closest valid resolution available), with differing levels of image quality. The results we report are for the highest resolution and detail level with which the product can deliver a reasonably good framerate (about 45 frames per second). Integrated graphics from Intel and AMD are depicted in blue and red respectively while discrete graphics has been assigned purple.

For the past couple of years, we've only compared integrated graphics to other integrated models and a single discrete card, a Radeon HD 6570 (equivalent to a US$40 model these days), and only using modest screen resolutions. That has to change with Iris Pro 6200 as it simply knocks them all out of the water. It plays all of our tests well at ~1600x900, sometimes putting out twice the average framerate of the HD 4600. It's also significantly faster than the last generation of Iris Pro graphics found on the i7-4770R.

We arrived at our overall gaming performance rating by giving each GPU a proportional score in each gaming benchmark with each test having an equal weighting. The scale has been adjusted so that the i7-6700K's HD 530 graphics (Skylake) is the reference point with a score of 100.

Overall there is a 90% improvement compared to the new i7-6700K. It's even more impressive against Haswell with the i7-5775C doubling the performance of the i7-4770K.

Iris Pro 6200 sets itself apart as the first integrated graphics solution that can handle all of our benchmarks comfortably at 1080p resolution. As such, it's deserving of better competition, a trio of older discrete cards, the Radeon HD 7750, GeForce GTS 450 and GeForce GT 640. The same CPU was used for the Nvidia cards while the AMD model was tested with our Skylake platform as it inexplicably wouldn't boot with our Z97 board. This won't matter as none of these games are CPU-bound with this class of processor.

To our surprise, it renders our most demanding game, Aliens vs. Predator with the best average framerate and also posts strong results in Just Cause 2 and Resident Evil 5. Its performance is noticeably superior to the Zotac GT 640 ZONE which is paired with DDR3 memory. If I had to guess, I would estimate it's on par with the GDDR5 version of the same model, or its successor, the GT 740, which can be found for as low as US$70.

Gaming with the integrated graphics isn't necessarily more power efficient either as the system power consumption of the Iris Pro 6200 machine is consistantly over 100W, more than both the GT 640 and HD 7750 configurations.

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