Intel Core i7-7740X
$500 | WWW.INTEL.COM.AU It’s a lot cheaper than its Core i9 sibling, but can this X-series Core i7 stand up to its regular counterpart?
Like its Kaby Lake-X stablemate, the Core i7-7740X has a tough task to justify its existence. For the hardcore overclockers, it unleashes further potential from the Kaby Lake silicon, previously withheld by the LGA 1151 socket and associated Z270 boards that the Kaby Lake-S Core i7-7700K calls home.
Also like the i5-7640X, the i7-7740X receives a slight base frequency increase, moving from 4.2GHz to 4.3GHz, while retaining the same 4.5GHz boost frequency as its Core i7-7700K brethren. Paired with an increase of stock RAM frequency from DDR4-2400 to DDR4-2666 in a one DIMM per channel configuration, the i7-7740X looks like an attractive option. However, this view becomes muddied, as when paired with effective cooling, the CPUs spend the majority of processing load time operating at the boost frequency. Furthermore, whether on X299 with Kaby Lake-X or Z270 with Kaby Lake-S (K SKU), most users will be running overclocked RAM frequencies, exceeding the stock spec. Basically, the stock RAM speed bump is a redundant addition.
Overclocking is the call to purpose for the i7-7740X. Like the i5-7640X, it makes the most of the supporting motherboard power delivery hardware, namely the socket and VRM, to provide a significantly higher performance ceiling when overclocking. During testing for the i7-7700K and Z270 launch feature in APC 437, our i7-7700K sample established a functional, consistent overclock of 4.7GHz, topping out at 4.8GHz but crashing in some tests due to the summer heat. By comparison, testing the i7-7740X and X299 delivered a functional, consistent overclock of 5.1GHz and topping out at 5.2GHz with some heatrelated crashes and scraping into the operating system at 5.4GHz at 1.40v before the dreaded blue screen of death hit. We found 5.0GHz to be the sweet-spot.
Another key difference for the Kaby Lake-X offerings over the S models is the removal of the integrated graphics processing unit for the X chips. This is a moot point for most, given the association of Core i7 CPU use with discrete GPUs (like the Nvidia GeForce GTX 1080 Ti we used in testing) and simply a fact of the Intel X platform not supporting iGPU implementations.
We welcome the improved overclocking capability, yet we view the i7-7740X implementation as a glass half full scenario. The reasoning behind this is linked to the low PCIe lane count for direct-to-CPU communications. Even with the 24 PCIe 3.0 lanes from the X299 PCH, the fact the i7-7740X only sports 16 direct-to-CPU PCIe lanes makes for tricky config and spec planning to ensure all planned resource implementation can be supported by the platform. If considering a Kaby Lake-X purchase, we strongly advise pre-planning resource allocation and thoroughly reviewing the motherboard manual for lane allocation, lest you be disappointed upon realising shared resources.
Overall, it’s a fun platform from a toy perspective, but lacking fiscal viability compared with an equivalent i7-7700K/Z270 solution and resource viability from a HEDT solution angle.