Testbed and Methods

New Noctua NH-C12P cooler and its competitor – Thermalright SI-128 – were tested in two modes: in an open testbed when the mainboard sits horizontally on the desk and the cooler is installed vertically, and in a closed testbed with the mainboard in vertical position. In the latter case both coolers were installed with the ends of their heatpipes facing upwards.

Our testbed was identical for all coolers and featured the following configuration:

• Mainboard: ASUSTek P5K Deluxe/WiFi-AP (Intel P35), LGA 775, BIOS 0812
• Processor: Intel Core 2 Extreme QX9650 (3.0GHz, 1.25V, 2x6MB L2 cache, 4x333MHz FSB, Yorkfield, C0)
• Thermal interface: Arctic Silver 5
• Graphics card: Chaintech GeForce 9800 GTX GDDR3 512MB / 256bit, 675/2200MHz
• Graphics card cooler: Arctic Cooling Accelero S1 + Turbo Module
• Memory:
  • 2 x 1024MB DDR2 Corsair Dominator TWIN2X2048-9136C5D (1142MHz / 5-5-5-18 / 2.1V);
  • 2 x 1024MB DDR2 CSXO-XAC-1200-2GB-KIT DIABLO (1200MHz / 5-5-5-16 / 2.4V).
• Disk subsystem: Samsung HD501LJ (SATA-II, 500GB storage capacity, 7200rpm, 16MB cache, NCQ)
• Optical drive: Samsung SH-S183L SATA-II DVD RAM & DVD±R/RW & CD±RW
• System case: System case: ASUS ASCOT 6AR2-B Black&Silver (ATX) with 120mm ~960RPM Scythe Slip Stream fans for air intake and exhaust (the fans are installed on silicon spindles), and the same 120mm ~800RPM fan on the side panel
• Control and monitoring panel: Zalman ZM-MFC2
• Power supply: Enermax Galaxy EGA1000EWL 1000W (a default 135mm fan for intake; and 80mm fan for air exhaust)

All tests were performed under Windows XP Professional Edition SP2. SpeedFan 4.34 Beta 44 was used to monitor the temperature of the CPU, reading it directly from the CPU core sensor:

The mainboard’s automatic fan speed management feature was disabled for the time of the tests in the mainboard BIOS. The CPU thermal throttling was controlled with the RightMark CPU Clock Utility version 2.35.0:

The CPU was heated up with OCCT (OverClock Checking Tool) version 2.0.0a in a 23-minute test with maximum CPU utilization, during which the system remained idle in the first 1 and last 4 minutes of the test:

I performed at least two cycles of tests and waited for approximately 20 minutes for the temperature inside the system case to stabilize during each test cycle. The stabilization period in an open testbed took about half the time. Despite the stabilization period, the result of the second test cycle was usually 0.5-1°C higher. The maximum temperature of the hottest CPU core of the four in the two test cycles was considered the final result (if the difference was no bigger than 1°C – otherwise the test was performed at least once again).

The ambient temperature was checked next to the system case with an electronic thermometer that allows monitoring the temperature changes over the past 6 hours. During our test session room temperatures varied between 21.0 ~ 21.5°C. It is used as a staring point on the diagrams. Note that the fan rotation speeds as shown in the diagrams are the average readings reported by SpeedFan, and not the official claimed fan specifications.

We tested Noctua NH-C12P with its original fan in three work modes. However, we also tested it with a few other fans, such as Scythe SlipStream 120 working at ~840RPM and ~2000RPM and Scythe Ultra Kaze running at ~1000RPM and ~2900RPM. The Austrian cooler’s competitor, Thermalright SI-128, was tested with the most suitable Ultra Kaze fan from Scythe in two identical modes. Now let’s discuss the obtained results.