Intel Core i7-875K And Core i5-655K Battle Beyond 4 GHz

AMD: Two CPUs At 4 GHz

Phenom II X6 1090T

Unlocked Phenom IIs are far less novel—AMD has been doing this for years.

No doubt, the excitement over seeing Intel follow suit stems from the company’s advanced manufacturing technology, which facilitates the massive scalability we got out of the Core i5-655K.

AMD’s 45 nm process is no slouch, though. The company was able to introduce a six-core processor at the same 125W TDP as previous quad-core models. According to AMD, this is a result of adding low-k dielectric material in the metal layers to reduce capacitance. Low-leakage parts mean less heat—and that’s good for overclocking on air (the high-end guys actually prefer high-leakage parts, since they overclock more aggressively, and dissipating heat using LN2 isn’t really a challenge).

I struggled to get the hexa-core 1090T stable at 4.3 GHz with Turbo CORE enabled. Then it was 4.2 or even 4.1 GHz. At each setting, general instability kept us from finishing testing (and heat wasn’t even the issue, despite voltages of up to 1.525V). At the end of the day, the X6 1090T was dialed in at 4 GHz with a voltage of 1.475V. The screenshot below was snapped before we started scaling back voltage at 4 GHz to minimize power use.

I won't be surprised if this chip doesn't make it to my next processor review, though. It was definitely ridden hard and put away wet.

Phenom II X4 965

Available under $200, the quad-core Phenom II X4 965 makes a good contender for the Core i5-655K (though it’s worth noting you can get a six-core Phenom II X6 1055T for less, as well; we simply haven’t purchased any yet).

Our 125W sample proved just as stubborn above 4 GHz as the Phenom II X6 1090T, despite our oversized cooler, 1.5V+ CPU VID, and 1.25V NB VID. Prime95 simply wouldn’t let this chip dig in at 4.2 or 4.1 GHz. Nevertheless, we were happy to settle down to a 1.4625V setting while retaining stability at 4 GHz.  

And with that, all four of our test subjects were running at 4 GHz or higher and ready for a dash through the gauntlet.

Chris Angelini is an Editor Emeritus at Tom's Hardware US. He edits hardware reviews and covers high-profile CPU and GPU launches.
  • xurwin
    BE vs K!! go K series
  • sarsoft
    LGA 1366 i7 hopefully will be available soon. GRRRRRRRRR........
  • Known2Bone
    wow now that is some serious over-clocking... and here i am trying to push my 955 up past 3.93. i would have liked to see some liquid cooling tossed in to spice things up and maybe one more 5970... great job Chris!
  • cangelini
    Known--I'll talk to Thomas about getting some of that going in his next System Builder Marathon piece. He loves liquid cooling =)
  • hok
    still love my 930...
  • Stardude82
    Intel did release the E6500K for the LGA 775, but only in Asia.

    The only good thing here is that these chips will probably ship with heat sinks that don't suck and a good price drop for the i7 870. Otherwise, who cares, FSB stability on decent P55 boards has not been a problem. What the socket really needs from Intel is a better chip-set, not easier overclockers.
  • nurgletheunclean
    9. All prize winners are responsible for taxes and other surcharges on the prizes they win.

    1099'd for $1499? I hate how contest prizes all have full MSRP on everything. Even if you win it end up costing you $500+ in taxes.
  • SpadeM
    Intel makes good cpus, that's a given. Their problem lies in the pricing of such chips. I mean if you could buy a processor because you want to overclock it then the locked but cheaper one is as good as the unlocked one. Sure, it's more difficult, but I for one love a challenge.

    Also, as a side note, I do have a problem with the benchmarks and more accurately with the conclusion you extracted from them. Who in their right mind would buy a processor, overclock it, and then do iTunes all day ... I mean come on, there's more to life then music ripping. What I'm saying is that the benchmark section SHOULD be remade entirely. Same old tests, that I could anticipate the outcome of every time, isn't a very compelling way to make a point. I do appreciate the game section though, at least i saw a new title.
  • jecastej
    Finally, very good news for serious desktop processing power that wont leave me with an empty wallet. The 875K is going to be my next CPU for 3D modeling and rendering. I hope it will keep me entertained for a while =)

    Don't get me wrong but I was getting bored with the tiny world of ARM and Tegra and on the other side of the spectrum the hexacores and dual Xeons were far and away for my budget.
  • anamaniac
    sarsoftLGA 1366 i7 hopefully will be available soon. GRRRRRRRRR........On, I just read about a guy reaching 4.644GHz on air with his i7 930. Granted, he has a great chip, but by no means is a unlocked multiplier needed for high overclocks.

    If I were to build a new PC, the 1090T/1055T would be very complelling.