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?

APC Australia - - Software -

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.


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