Intel Haswell-E Overclocking

One of the burgeoning questions relating to overclocking over the past couple of years has been the quality of Intel’s construction under the heatspreader relating to thermal interface material and adhesives. This caused enough of a talking point for Intel to release Devil’s Canyon (read our review here) which featured an upgraded interface and essentially reduced the thermal pressure restricting the overclock.

Thankfully Intel has not decided to play around with the extreme edition platform too much since Nehalem. Although recent reports suggest that Intel is using an epoxy to bind the die to the heatspreader, one tell-tale sign that a goopy TIM is not being used is the hole in the heatspreader in one of the corners.

Looking through the previous generations, Sandy-E, Ivy-E and Haswell-E shows this hole, which is typically thought to allow for expansion of the heatspreader and/or gas trapped inside due to the heat. Also due to the way that the epoxy is handled, the heatspreader cannot be removed without force and destroying parts the silicon die.

Due to the way that the CPU is arranged, with the cores to the left and right of center, there may develop a series of recommendations when using different methods of applying thermal paste as the sources of the heat will most likely be in these two regions. I would advise the normal procedure of applying thermal paste here: a small blob in the middle and allow the heatsink to spread the TIM through applied pressure. This helps remove air bubbles as the TIM spreads; spreading it out manually leads to air bubbles all over the place and is not recommended for high thermal sources.

In our results below we are using a Cooler Master Nepton 140XL closed loop liquid CPU cooler, and following the instructions above our CPU temperatures stay extremely low until we pile on the overclock. In fact I was seeing less than 30ºC while idle, which should bode well for overclocking.


Our standard overclocking methodology is as follows. We select the overclock options and test for stability with PovRay and OCCT to simulate high-end workloads. These stability tests aim to catch any immediate causes for memory or CPU errors.

For manual overclocks, based on the information gathered from stock testing, we start at a nominal voltage and CPU multiplier, and the multiplier is increased until the stability tests are failed. The CPU voltage is increased gradually until the stability tests are passed, and the process repeated until the motherboard reduces the multiplier automatically (due to safety protocol) or the CPU temperature reaches a stupidly high level (100ºC+). Our test bed is not in a case, which should push overclocks higher with fresher (cooler) air.


Due to the timing of our testing, we were only able to test two i7-5960X CPUs. Both of these were M0 stepping samples, the same as the retail stepping as far as we understand. The i7-5960X for reference is a 3.0 GHz base clock CPU with 8 cores, with a stock load voltage around 1.050 volts. Standard turbo modes allow 3.5 GHz, and so we start our testing at 3.5 GHz on all cores at 1.000 volts set in the BIOS. Where load line calibration was possible, it was enabled to match our setting as closely as possible, but otherwise only the CPU voltage was adjusted.

The first sample has a lot of early headroom with +0.100 volts allowing for an extra +1.1 GHz, or a 36.7% overclock. It has been a long while since numbers like +36.7% has been bandied around Intel’s extreme range, with only the i7-920 type Nehalem CPUs doing that sort of overclock in its stride.

The sweet spot for this CPU seems to be at around 4.4 GHz where the CPU voltage is just starting to rise but peak temperatures are under 75ºC.

Unfortunately our second sample was pretty much a dud by comparison. The voltage needed early on in the overclock went up quickly. This time we were unable to monitor temperatures due to a BIOS issue, but had a power meter on hand. We still managed a +1.1 GHz overclock easily enough, although +0.175 volts was required.

At 4.1 GHz, peak power is +104W over the system power draw at stock, with another 40W at 4.3 GHz. This shows that Haswell-E can be a power hog from even small overclocks, and thus users must have cooling to match. If we add the 140W TDP and the +140W more from the overclock (it would most likely be more than this due to the change of efficiency in the PSU curve), then a mildly overclocked CPU is fast approaching 300W. One can imagine that a highly clocked 4.7 GHz sample would be nearer 400W, and thus users should purchase power supplies to match.

A Problem with Haswell

One issue from Haswell does crop up with Haswell-E: the variability in the quality of the processors. Intel only guarantees that the processor will run at the specific frequency and voltage that is applied out of the factory: any other speed is out of specification and not supported. With Haswell LGA1150 CPUs, while the turbo frequency of the i7-4770K was 3.9 GHz, some CPUs barely managed 4.2 GHz for a 24/7 system.

If we consider that the i7-4770K only needs one of those CPU cores to be below quality to ruin overclockability, then placing double the cores on the i7-5960X is asking for double the trouble. Time to put some numbers to this:

In ASUS’ press deck for overclocking recommendations that came with the X99-Deluxe, they tell us the following:

i7-5960X at 4.4 GHz with 1.300 volts is below average
i7-5960X at 4.5 GHz with 1.300 volts is average
i7-5960X at 4.6 GHz with 1.300 volts is above average

By that standard our first CPU is around average and the second CPU we tested is below average. Even with these guidelines, it would seem that other reviewers and even manufacturers are getting a wide array of results. I have heard of reports of CPUs getting 4.7 GHz on a water loop, whereas others are testing a range of CPUs and not getting more than 4.4 GHz, like our second sample.

ASUS is recommending that anything over 1.25 volts requires a water/liquid cooling as a bare minimum, with up to 1.35V needing a triple (3x120mm) radiator setup depending on ambient temperatures. As with most overclocked setups, this means that the enthusiast user must decide between clock speed or fan noise for their machine.

Another issue with Haswell-E is the current draw of the CPU. ASUS is stating that the standard current draw for the CPU can reach 25 amps, meaning that the power supply must be capable of supplying at least 30 amps on the EPS12V cable. This is covered for most home-build non-OEM power supplies with an 80 PLUS rating, but suggests that a cheap power supply might trigger the over-current protection early.

Comparison to Ivy Bridge-E, Sandy Bridge-E, Haswell

As part of our testing, we hooked up our older i7-4960X and i7-3960X to the ASUS Rampage IV Black Edition, as well as compared to our previous i7-4790K Haswell overclocks:

Our i7-3960X sample at the time was actually a really nice overclocking CPU, in comparison to our i7-4960X which was below overage. I put two values here for the i7-5960X, showing that a 4.3 GHz overclock, while it is lower in number than the 4.8 GHz of the i7-3960X, is actually around the same percentage overclock. If we have a good i7-5960X for comparison, then +50% overclock comes very easily.

The next question then is which one is better for performance?  While the Haswell-E CPUs have a lower frequency than the previous generations, they do have the benefit of a higher IPC and DDR4 memory. There is also the core count, with the i7-5960X having 8 cores at 4.3/4.6 GHz against the six cores or four cores.

It should be obvious that for single core throughput, the i7-4790K wins at 4.7 GHz:

Kraken 1.1, Overclocked Results

FastStone Image Viewer 4.9, Overclocked Results

Dolphin Emulation Benchmark, Overclocked Results

3D Particle Movement: ST, Overclocked Results

In most benchmarks, the 5960X, 4960X and 3960X are actually evenly matched for single threaded performance, with the 5960X taking the edge on software that can take advantage of the newer instruction sets.

For multithreaded tasks, an overclocked i7-5960X is the only way to go:

HandBrake v0.9.9 2x4K, Overclocked Results

Agisoft PhotoScan - Total Time, Overclocked Results

Hybrid x265, 4K Video, Overclocked Results

The graphs later in the review comparing each of these processors at stock will have our overclocked results as well.

Evolution in Performance: IPC and Memory Bandwidth Power Consumption, Test Setup


View All Comments

  • Ian Cutress - Monday, September 1, 2014 - link

    When I tested the 5930K/5820K, the motherboard BIOSes were still very early alpha builds and did not allow overclocking. If I can get these CPUs in again to test (they had to be sent back), I will do some overclocking results for sure. Reply
  • jwcalla - Friday, August 29, 2014 - link

    Might as well wait for them to fix TSX at this point. Reply
  • iwod - Friday, August 29, 2014 - link

    How likely will this be in Mac Pro? Reply
  • DigitalFreak - Friday, August 29, 2014 - link

    Doubtful. Apple is using Xeons in the Mac Pro. Reply
  • hansmuff - Friday, August 29, 2014 - link

    I'll be waiting for two more generations. Maybe something worthwhile comes along to replace my 2600k at 4.4GHz. I'm glad the review shows so clearly where this new chip excels and who should save their money. Reply
  • Yuriman - Friday, August 29, 2014 - link

    "Modules should be available from DDR3-2133 to DDR3-3200 at launch, with the higher end of the spectrum being announced by both G.Skill and Corsair. See our DDR4 article later this week for more extensive testing."
  • TelstarTOS - Friday, August 29, 2014 - link

    Good article but the overclocking comparisons are a bit limited, i.e. 5930K and 5920K overclocking tables are not provided, nor a comparison with older SB/IB cpu @around 4,5ghz which most people still have and are deciding whether to upgrade to a X99 or a Z97 platform.
    A more accurate RAM performance comparison is also missing.
  • Ian Cutress - Monday, September 1, 2014 - link

    At the time I had the 5930K/5820K, I was not in a position to be able to overclock due to early alpha firmware. Due to our newer benchmarking suite, I still need to go back to the early Sandy (non-E) CPUs to retest. Anything you see in Bench with the power listed has been retested at least in part this year, depending on my scheduling. Unfortunately I don't have the space to have this as an ongoing project, it occurs in time with reviews. Reply
  • name99 - Friday, August 29, 2014 - link

    "For the six core models, the i7-5930K and the i7-5820K, one pair of cores is disabled; the pair which is disabled is not always constant, but will always be a left-to-right pair from the four rows as shown in the image. Unlike the Xeon range where sometimes the additional cache from disabled cores is still available, the L3 cache for these two cores will be disabled also."

    Are you sure that these various statements are correct? I'm not doubting you, but I would point out that at Hot Chips 2014 discussing the Xeon IVB server, Intel stated that they'd designed the floorplan to be "choppable".
    They gave a diagram that showed a base of fifteen (3x5) CPUs+L3 slices, which chop lines to take off a th3 right-hand 5 CPUs, then to take off one or two of the horizontal pairs (taking the 10 CPus down to 8 and then 6).

    Point is:
    - the impression they gave is that these reduced CPU counts are not (at least not PRIMARILY) from full dies with disabled (or nonfunctional) cores --- they are manufactured to have smaller area with fewer cores.
    - which suggests that versions with fewer cores but larger cache are some sort of anomaly (because the chop cuts out L3 slices along with cores). Perhaps THOSE are the chips that really did have one or two non-functional cores but with still functional L3 slices?
  • Ian Cutress - Monday, September 1, 2014 - link

    As far as we know, the floorplan for the die for i7 is an 8-core, with the 6-core models being disabled versions rather than wholly new dies.

    With the Ivy-E Xeons, there are a number of CPUs that have high L3 per core numbers due to the way the cores are disabled - Intel usually sticks to 3 floor plans or so depending on how their product line is stacked up. This may change with Haswell-E, though the Xeons have not been officially released yet. The Ivy-E floorplans can be found here, where I did a breakdown of L3/core:

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