5960x Overclock

[Michael Rosiles]

Inour testing to date, the average overclocked frequency for 5960X processors is 4.5GHz. Very good processors will achieve 4.6GHz fully stable with less than 1.30Vcore. Lesser samples achieve 4.4GHz with the same voltage:

Depending on your ambient temperatures, full-load voltages over 1.25Vcore fall into water-cooling territory (dual-radiator). With triple radiator water-cooling solutions, using up to 1.35Vcore is possible. For air cooling the value is much lower, limiting total overclock, so plan your cooling investment appropriately.

For overclocking 5960X processors, we recommend PSUs that can supply a minimum of 30 amps to EPS 12V. At 4.6GHz a 5960X can draw close to 25amps from the EPS12V connector under software load. Minimum recommended PSUs for Haswell-E are upwards of 1,000W if using more than one high performance GPU.

Users should avoid running Prime95 small FFTs on 5960X CPUs when overclocked. Over 4.4GHz, the Prime software pulls 400W of power through the CPU. It is possible this can cause internal degradation of processor components.

We use the ROG Realbench stress test, with the corresponding amount of installed memory selected in app. The stress test is equal or greater to alternatives, using real, open source apps with an oscillating load across the main PC subsystems.

The caveat to tuning DRAM voltage is that while memory is stable during a warm reset at 1.30V, a system power down or power cycle may be another matter. Often the training process from a full system shutdown requires a higher DRAM voltage to pass. For this reason we have created an additional setting for DRAM voltage on our boards.

Overclocking the cache frequency is not essential as processor core frequency dominates overall performance. However, if one wishes to experiment with cache overclocking - the cache frequency (AKA Uncore) can help boost some benchmark scores if run close to the processor core frequency.

From a methodology standpoint, it is wise to leave cache frequency at default whilst determining the maximum processor core frequency. Once the maximum processor core frequency has been found, one can start overclocking the cache. Following this method helps to isolate possible causes of instability for troubleshooting purposes.

We may need to apply a small boost to Vcore and VCCSA when the cache frequency is overclocked. This is because a faster cache ratio will increase the amount of data over the bus thanks to faster L3 cache access times.

2) If the stress test passes, apply XMP for the memory kit and repeat the stress test again. For most CPU samples there should be no need to make any VCCSA, DRAM voltage or memory timing adjustments- the stress test should pass. If it does not, then try tuning VCCSA; start with a manual voltage of 1.02V and work up or down.

The maximum DRAM voltage we use here in the lab for 24/7 table systems is 1.40V. Some modules may not scale with more voltage anyway. Good Hynix can handle higher voltage, but long term effects of running such voltage levels are unknown at this point.

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 30C 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 (100C+). 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.

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.

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:

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.

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.

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.

A few days before IDF 2014 in September, Intel launched their first 8-core desktop CPU, the i7 5960X Extreme Edition. The Haswell-E platform marries the Haswell microarchitecture we all know and love with DDR4, which we all have been anxiously awaiting. If you want to know more about the 5960X and X99 platform, you can take a look at Shawn's article here.

I have been overclocking and writing guides on cutting edge platforms since the Intel P67 chipset came out, however, X99 has proved to be an especially interesting challenge. Not only have I had to test out the new chipset and CPU, but I have also tested a new IMC and generation of DRAM. Most motherboards have had 6 to 8 BIOS releases since launch (about one a week), and I feel that the platform is now consistent enough to really take advantage of overclocking.

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