New Top-Cooler: Scythe Grand Kama Cross Review

During the past year 2009 we reviewed more than 45 (!) new air coolers for system CPUs. We have every right to say that cooling solutions are probably one of the most frequently tested PC components on our site. In fact, it is quite easy to explain this large amount of cooling related content, because efficient CPU cooling is the primary condition for successful CPU overclocking, which is exactly the goal of most users checking out cooler reviews.

You may be skeptical about it, but we are absolutely sure that cooling solutions makers will not slow down in the new 2010 and will continue mass launches of new cooling solutions with different price tags, acoustics and efficiency. Note that there is no need to wait for the processors designed for new socket form-factors and mainboards with different layout of cooler retention holes. All they need to do is modify the heatsinks a little, attach new fans, change the packaging, and here you are: the new cooler is ready. We are going to talk about it in one of our next articles. But today we are going to open e new cooler review season with an article on a truly new solution – Scythe Grand Kama Cross.

Package and Accessories

The cooler comes in a medium sized square cardboard box, which is covered with all sorts of information in a way typical of Scythe solutions.

Here you can read about the peculiarities of the cooling system, get the list of supported platforms. In other words, everything that can be disclosed about a cooler before the actual test session, is right there on the box.

The accessories bundled with the cooler are packed in a separate cardboard box at the bottom of the package:

• Universal retention plate for LGA775/1156/1366 mainboards;
• Retention plate for Socket 754/939/940/AM2(+)/AM3 mainboards;
• Retention plate for Socket 478 mainboards;
• Installation instructions;
• A 1 g pack of thick SilMORE thermal paste;
• Four retention screws.

The new cooler is made in Taiwan and is priced at $45 MSRP.

Design and Functionality

Scythe Grand Kama Cross design didn’t really change compared with the previous model – Scythe Kama Cross. The cooler still consists of two aluminum heatsinks installed at 45 degrees angle to the mainboard surface (the so-called X-structure). There is a fan attached above them.

However, the cooler has become significantly larger and heavier: instead of the 140x120x132 mm and 530 g it now measures 177x140x137 mm and weighs 750 g.

The heatsink plates have also changed. Now each of them consists of three parts of different height. The deeper beneath the fan is the heatsink array, the larger are its plates.

Scythe engineers have obviously tried to increase the effective cooling surface of the heatsink this way and make sure that the airflow from the fan is used with maximum efficiency.

There are total 72 plates pressed against the heatsink heatpipes (36 plates in each angled array). Each plate is 0.4 mm thick and the gaps between them are 2 mm.

There are also more copper heatpipes in this cooler model: this cooler uses an extra 6 mm heatpipe, so that there are four of them now instead of three used in Scythe Kama Cross. The heatpipes go through copper nickel-plated base, curve in a pretty sophisticated manner and pierce the heatsink arrays.

The base is covered with clear protective film that needs to be removed before installation. Slightly flattened heatpipes are soldered to the copper nickel-plated base, which is 4 mm thick. The base measures 38×38 mm. the finish quality of the base plate is remarkably impeccable.

As we have already mentioned before, the cooler is equipped with a 140x140x25 mm fan.

This fan model looks very similar to Scythe Kaze Maru fan, which we have already reviewed before; the same 9 broad blades and almost the same marking that reads SM1425SL12ML-P. The fan rotation speed is pulse-width modulation controlled (PWM) and according to the specs it lies between 500 and 1000 (±10 %) RPM. The fan generates between 9.6 and 24.7 dBA of noise and creates 27.2-69.93 CFM airflow. It uses a slide bearing that should guarantee up to 30,000 hours of worry-free operation. I would also like to add that the fan rotor is 39 mm in diameter and the fan comes with a 300 mm four-pin cable.

This fan has one more interesting peculiarity: its retention holes are the same as those of regular 120 mm fans. It means that if the default fan of the new Scythe Grand Kama Cross cooler breaks, you will be able to replace it with any 120 mm fan you have available, including 38 mm models.

Compatibility and Installation Tips

The cooler retention mechanism is very simple and our regular readers should already be very well familiar with it. There are three types of retention plates that need to be screwed on to the cooler base with four enclosed screws.

So, Scythe Grand Kama Cross supports all contemporary platforms without any exceptions and even one outdated Socket 478 platform. Of course, the reliability of these retention kits leaves much to be desired. It is especially true about the retentions for the contemporary Intel CPUs using plastic push-pins. However, there is a good thing about it, too: there is no need to remove the mainboard from the system case to install the processor cooler onto any type of platform.

When Grand Kama Cross is installed, its heatsinks turn out pretty high above the mainboard surface that is why they do not interfere with the tall heatsinks over mainboard voltage regulator components as well as heat-spreaders on memory DIMMs.

According to the manual, the preferable cooler position inside the system case ensuring maximum efficiency is when the heatpipes are positioned in parallel to the top edge of the mainboard, so that both heatsink arrays could be turned along the same horizontal axis.

It is true, if the cooler is positioned not the way it is shown on the photo above, but rotated by 90 degrees, it gets 4°C less efficient under maximum processor load and the lower heatsink array with heatpipes warms up noticeably less than the top one.

Testbed and Methods

We are going to test the cooling efficiency of Scythe Grand Kama Cross and its competitors in a following testbed:

• Mainboard: ASUS P6T Deluxe (Intel X58 Express), LGA 1366, BIOS 1804;
• Processor: Intel Core i7-920, 2.67 GHz, 1.25 V, 4 x 256 KB L2, 8MB L3 (Bloomfield, C0);
• Thermal interface: Tuniq TX-2;
• Graphics card: ATI Radeon HD 5850 1 GB GDDR5, 725/4000 MHz;
• Memory: DDR3 3 x 2 GB OCZ Platinum Low-Voltage Triple Channel (Spec: 1600 MHz / 7-7-7-24 / 1.65 V);
• System HDD: Western Digital VelociRaptor (SATA-II, 300 GB storage capacity, 10,000 RPM, 16 MB cache, NCQ) inside Scythe Quiet Drive 3.5” silencer and cooler chassis;
• System case: Antec Twelve Hundred (front panel: two Noiseblocker NB-Multiframe S-Series MF12-S1 fans at 900 RPM and Scythe Gentle Typhoon fan at 900 RPM; back panel: two Scythe SlipStream 120 fans at 900 RPM; top panel: standard 200 mm fan at 400 RPM);
• Control and monitoring panel: Zalman ZM-MFC2;
• Power supply: Zalman ZM1000-HP 1000 W (with a default 140 mm fan).

During this test session we managed to overclock our 45nm quad-core processor (with polished heat-spreader) with the multiplier set at 21x and “Load-Line Calibration” enabled to 3.97 GHz using the weakest cooler of the testing participants. The nominal processor Vcore was increased to 1.35 V in the mainboard BIOS.

The memory voltage was at 1.64 V and its frequency was around 1.5 GHz (7-7-7-14_1T timings). All other parameters available in the mainboard BIOS and connected with CPU or memory overclocking remained unchanged (set to Auto).

All tests were performed under Windows 7 RTM x64 operating system. We used the following software during our test session:

• Linpack 64-bit with LinX shell version 0.6.4 – to create maximum CPU load (5 Linpack runs in each cycle with 3584 MB RAM capacity involved);
• CPU-Z 1.53 – to monitor processor core voltage and frequency;
• Real Temp 3.50 RC6 – to monitor the processor core temperature;
• Everest 5.30.1977b – to monitor default fans rotation speeds.

The CPU was loaded with two consecutive Linpack test runs with the settings as indicated above. The stabilization period for the CPU temperature between the two test cycles was about 8-10 minutes. We took the maximum temperature of the hottest processor core of the four for the results charts. The ambient temperature was checked next to the system case with an electronic thermometer with 0.1 °C precision that allows monitoring the temperature changes over the past 6 hours. During our test session room temperature was at 24.6-25.0 °C.

The noise level of each cooler was measured after 1:00 AM in a closed room about 20 m2 big using CENTER-321 electronic noise meter. The noise level for each cooler was tested outside the system case when the only noise sources in the lab were the cooler and its fan(s). The noise meter was installed on a tripod and was always at a 200 mm distance from the cooler fan. To measure the noise we set the cooler onto a 45 mm stand made of polyurethane foam material on top of a desk. The lowest noise reading our noise meter device can register is 29.8 dBA and the subjectively comfortable noise level in these testing conditions was around 34.5 dBA (do not mix it up with low noise level). The fan(s) rotation speed was measured in the entire supported range using the new controller revision by changing the voltage in the interval from 4 to 12 V with 0.5 V increment.

For comparison purposes we also included the results for the best top-cooler – XILENCE Black Hawk Copper and the best tower-cooler – Noctua NH-D14.

The first cooler was tested with a default fan, while the second one – with two 140 mm Noctua NF-P14 fans. It is obvious that these two reference coolers, the best in their class, do not compare against our today’s hero, Scythe Grand Kama Cross in price. But the price-point comparison is not our ultimate goal today. We intend to find out how much our today’s hero will yield to the leaders. By the way, the first cooler was also tested with a powerful 140 mm fan from Ice Hammer cooler.

All coolers were tested in two modes: in subjectively quiet mode and at maximum fan rotation speeds. It would also be interesting to compare Scythe Grand Kama Cross against the predecessor, Scythe Kama Cross, but unfortunately, we didn’t have the latter in our lab at the time of tests.

Performance

Cooling Efficiency Tests

Before we move on to the actual benchmark results, let us offer you two screenshots showing the results obtained for Scythe Grand Kama Cross in a closed system case (on the left) and inside a system case with the side panel removed (on the right).

As you see, the difference is 7°C in favor of the open system case! Note that Antec Twelve Hundred case that we use as part of our regular testbed is one of the best (if not the absolute best) case in terms of internal structure and organization. Nevertheless, cases like that do restrict the cooling efficiency of tall top-coolers, while tower-coolers do not lose more than 2°C inside them. Therefore, we decided to perform our comparative tests in a case with a removed side panel. Here are the results.

Scythe Grand Kama Cross turned out a very good cooler that barely yields to a fully copper XILENCE Black Hawk Copper that costs and weighs twice as much. Note that the use of a powerful 140 mm Ice Hammer fan doesn’t help increase the cooling efficiency of Scythe Grand Kama Cross, which indicates that Scythe Kaze Maru was a perfect choice for this cooler. Unfortunately, the cooling efficiency of the best top-coolers is way below that of the best tower solutions. Noctua NH-D14 proves about 10°C more efficient in quiet mode and 7-9°C at maximum fan rotation speed.

Acoustic Performance

The results of our acoustic tests for two top-coolers in the entire supported rotation speed range of their default fans are given on the diagram below.

The quietest one was the frameless 38 mm fan of the XILENCE Black Hawk Copper. Up until 850 RPM the 140 mm fan of the Scythe Grand Kama Cross can compete against it quite successfully, but we can still hear a slight crackling of the motor, which the fan of the Black Hawk cooler doesn’t have. Moreover, Scythe fan features very unstable acoustics, when the change in the fan rotation speed would either have no effect on the noise level at all or would cause it to increase immediately, which you could hear even without any noise measuring devices involved.

Conclusion

Scythe Grand Kama Cross is a very efficient cooling solution that will definitely be of interest to computer enthusiasts and overclocking fans. Two independent heatsink arrays and a 140 mm fan allow the aluminum Grand Kama Cross to compete successfully against the today’s best top-cooler – XILENCE Black Hawk Copper, which is made of solid copper and costs twice as much.

As for the drawbacks about Scythe Grand Kama Cross, we could mention not the best retention solution for LGA775/1156/1366 platforms and a fan with non-linear dependence of the noise level on the fan rotation speed, which could, however, be peculiar only for our particular cooler sample.

Anyway, we are really excited about the upcoming new Scythe cooling solutions and look forward to checking them out this year!