In­tel Core i7-7820X

Why some CPU cores are more equal than oth­ers.

APC Australia - - Contents - Jeremy Laird

Eigh­teen months ago, eight cores was as good as it got for desk­top CPUs. Not now. In this brave new post-AMD Ryzen world, it’s half as many cores as AMD now sells you in a sin­gle CPU. It’s not even half as many as In­tel is plan­ning by the end of 2017.

The new Core i7-7820 is In­tel’s lat­est eight-core chip, and it ar­rives with a street price of around $799. That’s not only close to dou­ble the cost of that Ryzen pro­ces­sor, it’s also $300 more than the next CPU down in In­tel’s new Sky­lake-X range, the six-core Core i7-7800X. Of course, not all CPU cores are equal. Hold that thought while we look at the 7820X’s vi­tal sta­tis­tics.

Be­yond the eight cores and Hy­per-Threadin­gen­abled 16 threads, the head­line num­bers look good. There’s a 3.6GHz base clock, 4.3GHz Turbo clock, and 4.5GHz Tur­boMax speed. In other words, the 7820X packs a healthy combo of core-based par­al­lel­ism plus ex­cel­lent sin­gle-core clock speeds. You also get 28 PCI Ex­press lanes. OK, that’s way fewer than the 64 you get with an AMD Threadripper chip, and it’s a lot fewer than the 44 lanes In­tel hooks up to the next CPU up in its own Sky­lake-X lineup, the 7900X. But it’s prob­a­bly enough for all but the most de­mand­ing of sys­tem con­fig­u­ra­tions.

Of course, the other ma­jor fea­ture that comes with the 7820X is In­tel’s peer­less CPU core ar­chi­tec­ture. AMD’s Ryzen cores are very good, but they’re not quite this good. Which is why the 7820X blows ev­ery eight­core Ryzen CPU we’ve tested out of the wa­ter. OK, it’s only a lit­tle ahead of AMD’s fastest eight-core model, the Ryzen 7 1800X, in Cinebench’s mul­ti­thread­ing mode, and the 7820X only has a small ad­van­tage for video en­cod­ing, too. But it bat­ters the AMD chip by 194 points to 159 in Cinebench’s sin­gle-threaded mode. That’s over 20% more per­for­mance.

In cer­tain mul­ti­threaded work­loads, it’s a lot quicker, too. Fry Ren­der gives the 7820X a 31% ad­van­tage for ren­der­ing. As for gam­ing, well, the raw num­bers would have you think­ing there’s not much in it. In prac­tice, AMD’s mod­u­lar Zen ar­chi­tec­ture can be stut­tery in some game ti­tles. It’s not a wide­spread is­sue, but In­tel re­mains the ob­vi­ous choice for con­sis­tently smooth per­for­mance in the widest num­ber of games.

All of that ap­plies to the 7820X run­ning at stan­dard clock speeds. Thanks to an un­locked CPU mul­ti­plier, you have easy ac­cess to crank­ing up the fre­quen­cies, too, if that’s your bag. In the end, then, In­tel’s mar­ket­ing boys aren’t com­pletely crazy. Yes, the 7820X looks ex­pen­sive in terms of pure core count, when you can grab an AMD eight-core CPU for half the money, but there’s more to CPU per­for­mance than mere core count. In­tel’s cores re­main the best you can buy on a per-core ba­sis, and that, com­bined with healthy clock speeds, means the Core i7-7820X is quicker than any cur­rent eight-core AMD pro­ces­sor.

That goes some way to jus­ti­fy­ing the price. Whether it gets you over the line and makes the 7820X a com­pletely com­pelling propo­si­tion will come down to your us­age sce­nario. If all you care about, for in­stance, is video en­cod­ing, this chip prob­a­bly isn’t for you. But as an all-round work­horse, it’s a se­ri­ously nice CPU.

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