New Mid-Priced Coolers from OCZ and Scythe: The Small and the X of It

New CPU Cooling Test Configuration

All Cooling tests were run on the new cooling test bed, which is a Rosewill R604-P-SL case sold without a power supply. The Rosewill is a www.newegg.com brand typical of a moderately priced mid-tower case our readers might own. It was chosen because it is a Newegg top seller and includes a variable front intake louver and a quiet 120mm exhaust fan at the rear of the case. The case is also screwless with components held in place by plastic holders instead of metal to metal connections. This appears to reduce case vibration and noise.

The new power supply is a Corsair HX620W, which has earned our respect as an exceptionally quiet PSU with a variable speed exhaust fan and a down-facing fan mounted just above the CPU space in the case. To eliminate the video card as a source of noise we have moved to a fanless video card. Since the move will be made to Vista and DX10 in the near future, the testbed runs an MSI NX8600GTS which supports DX10 and cools with heatsinks and heatpipes. The reduced noise power supply and fanless video card have the potential to dramatically lower system noise in the test bed.

The new motherboard is the Asus P5K Deluxe. This P35 chipset motherboard has exhibited outstanding overclocking capabilities in our testing, and it can also mount the newest 1333 FSB Intel Core processors and can handle our existing high-speed DDR2 memory. The P5K3 uses heatsinks and heatpipes to cool board components so all motherboard cooling is passive. There are no active cooling fans.

Other components in the cooling test bed are generally the same as those used in our previous motherboard and memory test bed. The goal was to remove fans that might produce noise wherever possible, improve internal airflow, reduce the power supply noise floor, and eliminate the video card as a noise source.

The 120mm exhaust fan mounted to the rear of the case is below the system noise floor. We run that fan during performance and overclocking tests. However, system noise can be cumulative, so the exhaust fan is turned off during noise testing. The current fan will be replaced by the lowest noise 120mm fan when our 120mm fan roundup is completed.

Cooling Performance Test Configuration
Processor	Intel Core 2 Duo X6800 (Dual-core 2.93GHz, 4MB Unified Cache)
RAM	2x1GB Corsair Dominator PC2-8888 (DDR2-1111)
Hard Drive(s)	Hitachi 250GB SATA2 enabled (16MB Buffer)
Video Card	MSI NX8600GTS (fanless) - All Standard Tests
Intel TAT	Version 2.05.2006.0427
CoreTemp	Version 0.95
Video Drivers	NVIDIA 163.71
CPU Cooling	OCZ Vendetta Scythe Kama Cross Swiftech H2O-120 Compact Corsair Nautilus 500 Thermalright Ultima-90 Thermalright Ultra-120 eXtreme Intel Retail HSF for X6800
Power Supply	Corsair HX620W
Motherboards	Asus P5K Deluxe (Intel P35)
Operating System	Windows XP Professional SP2
BIOS	Asus AMI 0501 (06/26/2007)

All cooling tests are run with the components mounted in a standard mid-tower case. The idle and stress temperature tests are run with the case closed and standing as it would in most home setups. We do not use auxiliary fans in the test cooling case, except for the aforementioned case fan. Room temperature is measured before beginning the cooler tests and is maintained in the 20 to 22C (68 to 72F) range for all testing.

For consistency of test results we tested with our standard premium silver-colored thermal compound. In our experience the thermal compound used makes little to no difference in cooling test results. This is particularly true now that processors ship with a large manufacturer-installed heatspreader. Our current test procedure uses this standard high-quality silver-colored thermal paste for all cooler reviews.

We first tested the stock Intel air cooler at standard X6800 speed and measured the CPU temperature at idle. The CPU was then stressed by running continuous loops of the Far Cry River demo. The same tests were repeated at the highest stable overclock we could achieve with the stock cooler. Stable in this case meant the ability to handle our Far Cry looping for at least 30 minutes.

The same benchmarks are then run on the coolers under test at stock, highest stock cooler OC speed (3.73GHz) and the highest OC that could be achieved in the same setup with the cooler being tested. This allows measurement of the cooling efficiency of the test unit compared to stock and the improvement in overclocking capabilities, if any, from using the test cooler.

The cooling test results of both the OCZ Vendetta and the Scythe Kama Cross are compared to a representative sample of air and water cooling results that were measured with CoreTemp. TAT provides a similar core measurement, but test results with CoreTemp were more consistent over a wide range of test conditions than the results reported by TAT. Coolers retested with CoreTemp under idle and load conditions were the Intel retail cooler, the Thermalright Ultra-120 eXtreme, and the Thermalright Ultima-90. The Ultra-120 eXtreme is the best performing air cooler tested at AnandTech, where the Ultima-90 is a smaller cooler that matches performance of other top coolers when fitted with a 120mm fan. Two recently tested entry-level water cooling systems are also included, along with results from tests of the OCZ Vendetta and Scythe Kama Cross.

In benchmarks where the new test bed makes no apparent difference, like maximum overclock, results are reported for all coolers tested this year.

Noise Levels

In addition to cooling efficiency and overclocking abilities, users shopping for CPU cooling solutions may also be interested in the noise levels of the cooling devices they are considering. Noise levels are measured with the case on its side and are measured using a C.E.M. DT-8850 Sound Level meter.

This meter allows accurate sound level measurements from 35bdB to 130dB with a resolution of 0.1dB and an accuracy of 1.5dB. This is sufficient for our needs in these tests, as measurement starts at the level of a relatively quiet room. Our own test room, with all computers and fans turned off, has a room noise level that has been reduced slightly to 35.0dB compared to the previous 36.4 dBA. With the new testbed, the system noise at idle is 36.5 dBA at 24" and 37.8 dBA at 6". This is better than our previous system noise floor of 38.3 db at 24". The noise reduction at the 6" distance is dramatically lower than the previous test bed floor of 47 dBA.

Procedures for measuring cooling system noise are described on page six which reports measured noise results comparing the stock Intel cooler and retested CPU coolers to the OCZ Vendetta and Scythe Kama Cross.