Intel Core i7 980X, Overclocked to 5 GHz

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In recent years we have written several times in a liquid nitrogen cooling systems and phase transition (phasechange). The goal has always been to have fun at increasing the frequency as much as possible, with the processor at the time. Some years ago, the 5 GHz was something "magical", but the arrival of Intel's 32 nanometer has achieved a similar frequency with air cooling. In this regard you can read our review on the i5 Core 655K, air-cooled and able to boot despite the frequency of 4.93 GHz Intel Core i7 875K and Core i5 655K, economic overclock. Overclocking a dual-core processor at high frequencies with an extreme cooling now does not make much sense, so we decided to put to the test with a 980X Core i7 Extreme Edition processor with six cores tip (for now) from Intel.

Most of you know the basic principles of cooling phasechange: the gases absorb heat during the expansion, and thus cool the surrounding area. A compressed gas in liquid absorbs more heat and changes phase back to its gaseous state, in the same way that water absorbs a large amount of energy it boils. The gas, in a similar manner, emit heat during compression is for this reason that conventional refrigerators and air conditioners use an external radiator to remove heat from the gas after they are compressed. The cooling brings the gas compressed in the liquid state, justifying the term "condenser" to indicate the hot side of the radiator. The evaporator is the element that distinguishes a cooling phase transition from a traditional cooling for CPU or an air conditioner. Heat exchangers for gas-to-gas appliances such recall a second radiator, and a CPU cooler uses a much smaller evaporator to remove heat from the CPU. What looks like a piece of copper pipe at the end of a drive image above is an evaporation chamber empty, connected to two lines: a high pressure, which provides the liquid, and a low pressure that moves the resulting gas.

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The six-core processor Intel Core i7 980X requires a motherboard with socket LGA 1366. Among the motherboards we tested, we chose X58A-UD7 Gigabyte, which has offered us the best stability. To test the differences in performance of a single processor at various speeds should not require faster RAM, but we used to eliminate a potential variable. Do not require a high-end graphics card for this test, but we did not want the system appear slow in the benchmark with video games. The Radeon HD 5850 delivers more than adequate at high settings. Cooling Cooler Express is accompanied by a guide for installation, per socket without a back plate support, or in the case of AMD, whose plate has been removed at the factory.

Four mounting screws go through the back plate, with the addition of four plastic spacers that prevent the breakdown of insulation sheets included. These spacers do not seem to fit in the case of socket LGA 1156 and 1366, but we did not change. A thin layer of insulating foam was then placed over the plate, followed by the element of heating. This prevents moisture condensation on the back of the motherboard when the CPU cooler cools the socket. The instructions say nothing about adding another layer of insulation, but the unit has been designed to be mounted on a flat surface. We put another thin piece of insulating foam to surround the original plate of the socket, filling the space between the motherboard and the original sheet of insulation. The screws of the cooling plate were then inserted through the mounting holes of the original CPU cooler places on the motherboard. Four nuts have enabled us to secure the assembly of this support, the plastic washers are used to avoid scratching the motherboard or damage its circuitry.

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Not having an insulation to seal one side were exposed to condensation, but we continued to follow the manual and we used duct tape, placed around the top of the socket. A final barrier insulation is designed to seal the top of the CPU socket from the bottom of the evaporator mounting block, but it seems too thin. During the processes described in the preceding pages, we put a layer of Zalman ZM-STG1 thermal paste on the CPU. Four springs placed over the screws for the assembly of the support slide into the recesses on the mounting block. The springs are topped by four plastic washers. Four mounting nuts tighten the springs, so the central unit, the evaporator, it is "pressed" against the CPU. The manual Cooler Express reminds us that it is important to dry the board at the end of each day. Hoping to do a full day of testing prior to accumulate enough water to short circuit the motherboard and your CPU, we booted the system and began testing. After about four hours the system has started to give problems.

We have already shown that we are not afraid to take risks and we have complete familiarity with the methods that should prevent moisture from accumulating in these areas fragili.Tra are painting the entire motherboard with a non-conductive sealant, isolation of the entire area around the CPU with non-conductive adhesive as the rubber gasket and the use of dielectric grease to the LGA. Unfortunately some of these solutions can not be removed from the motherboard. We needed that our system works for 12 hour intervals, but for a more extensive use recommend most of these precautions. The only drop of water that has locked the system has left a trace, leaving the evaporator and passing over the hole in the barrier of foam, up to our side of the CPU socket and into the Land Grid Array (LGA). The non-conductive adhesive was added to close the gap between the CPU cooler and the pressure plate of the socket. A new layer of duct tape sealing the area of the CPU through the layers of foam. The sheet of foam with the internal forum has been reinstalled on this tape. A drop of glue fills the space between the mounting block of the evaporator and the top sheet of foam. These minor changes have allowed our system to work for eight hours, but not for all 12 hours.

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The 980X Core i7 running at 3.33 GHz but the Turbo Boost increases its frequency to 3.6 GHz or 3.7 automatically depending on the number of cores used and the workload. The image you see below does not show exactly why the 3.466 MHz Gigabyte has not set the base clock 133.33 MHz motherboard clock sets the basic standard 135 MHz, while the manual settings we have brought the rate to 133 MHz. The highest temperature of your CPU to default settings, with -12 degrees Celsius, it went beyond the scale of our digital thermal sensor. Temperatures so cold we could not draw in real time through our system, however, was able to tell us that the CPU was warmer than the evaporator, where the temperature, -50 °, was reported by the Status Monitor Cooler Express. We reduced our threshold voltage for Intel 32-nanometer to 1.35 volts, after setting always 1.375 volt. But reference tests are done with air cooling and processors gain tolerance to tension with the temperature reduction. We used the limit of 1.35 volts as a starting point for this test with extreme cooling.

The voltage of 1.35 volts already pushes the CPU temperature under load on positive numbers and we started to wonder whether the imperfections on the surface of the evaporator temperature should be resolved in order to keep profits moving forward. The CPU has performed admirably in, reaching 4.46 GHz with a 100% stability. The next step was the 1.45 volts, which allowed us to achieve stability under load to 4.69 GHz with Hyper-Threading, which transformed our six physical cores in 12 logical cores. Temperatures were still acceptable, only a few degrees beyond the results obtained to 1.35 volts. The normal prudence would have advised us to stop there, but we are committed to finding the limit of the processor or reach 5 GHz, depending on which one comes first.

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A bit of additional tests have led to 4.9 GHz to 1.6 volts and have unveiled new limits of thermal stability. Even the slight increase in voltage would lead our CPU to 39 degrees Celsius, and even a slight increase in speed would reduce the temperature at which the CPU is reset. We had to reduce our temperatures. Some sites that deal with the recent cooling showed that thermal paste can reduce the temperature to 4 degrees to the Zalman ZM-STG1.Il our tests showed that it was necessary to decrease by at least 10°, to achieve full stability CPU 5 GHz The next logical step would be to smooth the joint surface of the evaporator through processes such as sandblasting and polishing, but we were not sure what this area was thin and we did not want to risk damaging products borrowed. We found another way to reach 5 GHz without producing more heat. We even managed to reduce it, disabling Hyper-Threading led us to have six rather than 12 physical cores. CPU temperature has dropped to about 20°.

The 980X has a Core i7 multiplier unlocked, but there is a value that can reach 5 GHz to 133 MHz frequency standard. We also wanted to maintain the memory frequency to ensure an accurate estimate of the CPU performance. Increase our rate base from 166.66 to 133.333 MHz would be the perfect solution, using a multiplier to 30 and 4 for the CPU to the DRAM in order to reach the 5 GHz and the frequency 1333 MHz for the RAM. The Gigabyte motherboard does not use frequency based split, then the base clock is increased from 133 to 166 MHz.

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consumption and efficiency

The Core i7 980X does not consume much frequency standard. Our entire system took only 104 watts at idle and 202 watts with 12 threads of Prime95. Consumption starts to rise beyond the voltage of 1.35 volts. Can not be a good sign for overclocking which had a peak performance gain of about 50%. The average improvement in performance was much smaller than the peak gain, with the fastest drive in our configuration about 20% above the standard frequency. Intel does not joke when increasing the frequency and voltage levels of high-end products. We know that efficiency can be improved when the performance of an overclocked CPU go up more than their own consumption.

The overclock has changed over the years. The project carried out in this article shows that today it is easier to reach 5 GHz than in years past. Considering that even our initial overclock of 1.35 volts has led to increased consumption by 50% to reach a higher frequency of 25%, push the Core i7 980X moderately too expensive. Whereas in some cases may also improve overclocking performance per watt, it seems a very undesirable situation. In addition, we have not tried to overclock the Core i7 980X voltage standard, and we are sure that some of you will see a modest overclock does not affect efficiency. Finally there is a chapter of the expense. Our cooling from 900 € requires 480 watts in addition to those required by the rest of the PC. For 12 hours a day means 2102 KW / h only for the dissipation system: a value that is felt in the bill. Leave our computer on for 24 hours, perhaps with Folding @ home, will double the cost. If you overclock in an environment with air conditioning, the added energy consumed by your air conditioner can once again double the cost. Thus, while the proper preparation of the cooling system can make a practical phase-change in terms of longevity and service life, the high cost of cooling and improved performance makes it difficult to moderate a similar choice for continuous use.