Haswell overclocked: the Core i7-4770K at 4.7GHz
We’ve currently seen what the Primary i7-4770K can perf orm at its def ault rate of recurrence. Now, it is time
to exceed the chip’s stock acceleration.
K-collection Haswell processors provide overclockers with 3 ways to crank the CPU rate of recurrence.
Raising the Turbo multiplier may be the easiest path to increased clock speeds. T his adjustable targets the
CPU cores specif ically, so modif ications won’t af f ect other program parts. Multiplier tweaking has ended up
the pref erred overclocking technique f or the previous f ew generations of Intel CPUs, also it remains
theref ore f or Haswell.
T he CPU f requency may be the product of the multiplier and the bottom clock speed. Increasing the latter
can also produce higher core speeds. Nevertheless, the processor’s DMI and PCI Show interf aces
f urthermore derive their f requencies f rom the bottom clock. Fiddling with the bottom f requency leads to
those interf aces to perf orm out of spec, compromising stability potentially.
Haswell supports f oundation clock handle, but we’re told simply by multiple f olks within the motherboard
market that the number of usef ul f requencies is comparable to Ivy Bridge: yet another 5-10% at best.
Having said that, Haswell improves upon Ivy with the addition of a f oundation clock strap inherited f rom
Intel’s ultra-high-f inish Sandy Bridge-E processor. T his strap f unctions as a reduction gear f or the DMI and
PCI interf aces. It’s with the capacity of dividing the bottom f requency by 1.25, 1.66, or 2.5, allowing that
clock to be elevated to 125, 166, and 250MHz without messing with the chipset and peripheral links.
Well, that is the theory, anyhow. Asus inf orms us it hasn’t discovered an individual Haswell CPU with the
capacity of running a 250MHz f oundation clock. T he majority of chips will do 166MHz, it says, and 125MHz
ought to be a lock f or several of them. You need to visit a similar +/- 5-10% adjustment variety at each
With Z 87 boards supporting CPU boosts to 8GHz in ef f ective 100MHz increments via multiplier boosting,
there’s little have to touch the bottom clock or its associated strap. Only intense overclockers seeking to
set benchmark inf ormation should be worried about those settings.
Asus has tested a huge selection of Haswell CPUs within its ef f ort to user prof ile the chip f or auto-tuning
algorithms. Based on the motherboard maker, Intel’s new hotness includes a little much less overclocking
headroom than Ivy Bridge will. Perhaps more importantly, Haswell apparently has more variance f rom chip to
chip, especially in the voltages necessary to hit specif ic speeds.
Of the processors Asus has tested, 70% hit 4.5GHz, 30% reached 4.6GHz, and 20% made 4.7GHz. Just
10% were steady at 4.8GHz. Warmth is certainly reportedly the limiting element, and Asus recommends
utilizing a dual-f an drinking water cooler to avoid thermal throttling previous about 4.5GHz or even 1.25V.
Going beyond 1.35V is apparently problematic even f or high-end drinking water coolers.
Since we’ve a high-end drinking water cooler in-house, we made a decision to see how f ar it might get our
Core i7-4770K. It is a various chip compared to the one Scott usef ul f or his CPU benchmarks, and the test
conf iguration dif f ered slightly f rom his, as well. T he machine was predicated on Asus’ Z 87-PRO
motherboard and a GeForce 680 GT X DirectCU II graphics card. Corsair provided the Push GT 120GB SSD,
the AX850 power, and 16GB of Vengeance Pro memory.
Although the RAM is rated f or operation at boosts to 2400MHz, we conf ined ourselves to testing the limits
of the CPU. Both Asus and Gigabyte tell us that higher memory space speeds can control CPU
overclocking, so it may be worth exploring that dynamic in a separate article.
To help keep the CPU cool, we used Corsair’s H80 drinking water cooler. T he radiator is not a double-wide
af f air, nonetheless it will be sandwiched between double f ans. We f urthermore swapped the share spinners
f or Corsair’s Atmosphere Series SP120 units.
We kept issues simple because of this round of testing and small ourselves to manually tweaking
conf igurations via the motherboard f irmware. A variety of AIDA64′s CPU stress ensure that you the Unigine
Character benchmark was utilized to test stability.
To start, we let the motherboard select CPU voltages automatically as we raised the multiplier. We made it
up to 4.2GHz without problem, and CPU-Z reported a new CPU voltage of just one 1.2V at that
acceleration. T he machine blue-screened at as soon as we started our stress test at 4.3GHz, though.
Establishing the CPU voltage to at least one 1.25V kept the loaded program stable f or two minutes prior to
the next BSOD, thus we added more. In the f inal end, 4.3GHz required 1.275V.
T hat voltage bump was suf f icient to sustain our CPU around 4.5GHz. However, glowing blue displays at
4.6GHz f orced us to nudge the CPU around 1.3V. At 4.7GHz, the chip needed 1.35V, and its own core
temperatures spiked around 84°C with regularity-even with the drinking water cooler’s f ollowers and pump
going in complete blast. T hermal throttling didn’t rear its mind until we attempted f or 4.8GHz, though.
Keeping BSODs away at that speed needed 1.375V, and the excess voltage sent temperatures in to the
90s. No level of more tweaking produced a well balanced, throttle-f ree conf ig at 4.8GHz.
At 4.7GHz, the system was stable
enough to perf orm a handf ul of
benchmarks. T he x264 check crashed
on the initial run but f inished two
subsequent three-loop classes without
(Even though screenshot above shows
a new CPU voltage of just one 1.376V,
the CPU has been set to at least one
1.35V inside the f irmware. Asus’ AI Suite
sof tware program agreed with CPU-Z ’s
T he numbers are pretty close to what one might expect. Pushing the Core we7-4770K to 4.7GHz increases
perf ormance by 19-26%, that is in-line with the increase inside clock speeds. Our 4.7GHz overclock
computes to increases of 21% and 27%, respectively, on the chip’s optimum Turbo f requencies f or
solitary- and all-core loads.
As is always the case with overclocking, your mileage can vary greatly. T hat said, it’s well worth noting that
we strike 4.9GHz with a similarly early Ivy Bridge sample a new 12 months ago. T hat CPU required 1
also.35V, nonetheless it got by with a new dual-f an air cooler.
All indications indicate overclocked Haswell processors requiring even more intense cooling than their Ivy
predecessors. T he Primary i7-4770K has a higher T DP compared to the 3770K, but the associated heat is
also spread over a larger die area. T he 4770K’s T DP per area computes to 0.47W/mm², as the 3770K’s is
0.48W/mm². Haswell and Ivy seem to be on even f ooting in that regard. T he die layouts f ollow exactly the
same f undamental blueprint, as well.
Haswell and Ivy Bridge also use a similar interf ace material between their dies and external heat spreaders.
Intel used to hire a f luxless solder between those two items, nonetheless it switched to thermal paste with
We don’t possess a def initive description f or Haswell’s apparent dependence on most robust cooling,
however the chip’s integrated VRM may are likely involved. Voltage regulation was dealt with of f -chip in Ivy
Bridge, but Haswell provides it-and the connected heat-onboard the die. Integrated voltage regulation is
really a big section of Haswell’s attractiveness f or mobile platf orms. Regrettably, it may also control the
processor’s overclocking possible on the desktop.
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