AFTER LAST WEEK'S LOOK at the Core i5 750, which showed pretty decent results even without much tuning on the Asus Maximus III Gene mainboard, it was time to try out its faster sibling, the Core i7 870.
Not only does the i7 have a higher base clock at 2.93GHz, but it also has an even higher 5-step Turbo Boost capability with all four cores running all the time at 3.2GHz, assuming your cooling is decent, or one or two cores all the way up to 3.6GHz to accommodate one or two single-threaded applications. And if that's not enough then there's also HyperThreading to consider as well for those who love it, yours truly excluded.
Not bad at all, but how will it perform when tuned up, compared to its cheaper relative, the i5? Well, I used exactly the same setup this time too, except that I slightly tweaked the DRAM timing to CL7-7-7 at DDR3-1600, which Kingston DIMMs do smooth as silk. Also, I upgraded the graphics card to the fabulous Gigabyte GeForce GTX285 OC with 2 GB RAM, which is helpful when running 3D Mark.
Do remember that, unless you use the Nforce bridge, the P55 based mainboards only provide the 1 x PCIe x16 or 2 x PCIe x8 slot options, unlike the X58. On the other hand, they do have reduced latency as the PCIe bridge connects directly to the CPU, which helps a bit. Intel, how about designing a proper 40 PCIe v2 lanes total on the CPU chip next time?
I guess Intel had to play some serious positioning games. If it added the extra PCI lanes into the LGA1156 socket, that would have killed its high end X58 cash cow. Yet I feel that, come Sandy Bridge, it will have to accommodate the higher I/O expandability in the top-end CPU chips, which by then will be those with up to eight cores on the desktop.
(Note - I forgot to type "Core i7" into CPU-Z before running the test pictured above, but did remember to change it to "870". Not the first time nor certainly the last this will happen to us reviewers with this Lynnfield family of Intel processors, no doubt.)
I ran the Core i7 870 CPU in two modes. In the first, I used the auto-recommended 3.52GHz (160MHz base CLK x multiplier 22), which is ready in split seconds without any overclocking knowledge required. It also auto-sets the RAM to DDR3-1600, then it's up to you to play with the latency settings there. And, the CPU is still doing it all at 1.25 volts.
The other setting was a slightly higher clock with DDR3-1667 memory and 3.65GHz clock, where I also ran the 3DMark as well. Note the active Turbo Boost step at this speed setting (167.5 MHz CLK x multiplier 24). I set the CPU voltage up just a bit to 1.27 volts here as well. All the benchmarks were done at this speed.
As you can see, these are very good results, which go a ways into territory previously reserved to the overclocked flavours of the expensive Core i7 975XE, and it's with the fixed multiplier without much tweaking, if any.
The Core i7 870, the CPU chip alone, is nearly thrice the price of the Core i5 750. On the total high end system cost level, that would result in around 15 per cent higher total price, for, yes, around 15 per cent higher total CPU performance. In this respect, if you want the best from the socket 1156, this is not bad.
Now, as said, there's more to it, and we'll be working further to breach the 4GHz barrier with these processors as well. The AMD Phenom II family really has reason to worry here. There is no Phenom II CPU that even remotely comes anywhere near this - let's remember midrange - Core i7. µ
Rock solid performance for decent price, low PCIe latency.
I'd have liked 16 more PCIe lanes for full 2 x 16 SLI or Crossfire.
Intel's pushed AMD behind too far, we need lively competition!