Section 9: Calibrations
Default temperatures are rarely accurate. The following two part procedure is designed to achieve two objectives:
■ Provide minimum Ambient to Tcase Delta for accurate Tcase Idle Calibration.
■ Provide maximum Tcase to Tjunction Gradient for accurate Tjunction Load Calibration.
Note: It is preferred, but not required, that Calibrations be conducted as close to 22c Standard Ambient as possible, which provides a normal temperature ceiling, and maintains environmental consistency for comparing Idle and Load temperatures among processor variants and system platforms.
Prerequisites:
(A) CPU cooler correctly installed.
(B) Print this Section to use for BIOS settings and Calibrations.
(C) Record or photo or Save Profile all BIOS settings for quick restore when Calibrations are complete.
(D) Follow the Test Setup: (Standardized configuration for maximum cooling at Auto Vcore, Frequency and Multiplier).
Computer Case Covers = Removed
Computer Case Fans = Manual 100% RPM
CPU Fan = Manual 100% RPM
CPU Frequency = Auto (See Note 1: below) **
CPU Internal Thermal Control = Enabled
Enhanced C1 Control (C1E) = Enabled
Internet = Disconnected
Memory Frequency = Auto
PECI (If Equipped) = Enabled
Speedstep (EIST) = Enabled
Vcore = Auto (See Note 1: below) **
Vdimm = Auto
Windows Programs = Closed
Part 1: Calibration - Tcase Idle (Uses maximum cooling at minimum Vcore, Frequency and Multiplier)
** Note 1: If BIOS does not respond properly to Auto Vcore, Frequency and Multiplier settings, then use an appropriate combination of manual settings to provide the following in CPU-Z:
Core Voltage = 1.100 V
Core Speed = 1600 Mhz (Core i7 processors)
Core Speed = 1600 Mhz (Core 2 - 65 nm processors)
Core Speed = 2000 Mhz (Core 2 - 45 nm processors)
(A) Measure Ambient near the computer case air intake, clear of warm exhaust. A trusted indoor analog or digital thermometer will suffice. The accuracy of this device and measurement will determine the overall accuracy of the Calibrations.
(B) Boot into Windows. Close all programs, background processes, Screen Savers, SETI, Folding and Tray software. Press Ctrl-Alt-Delete, click on Task Manager, then click on the Performance tab to confirm CPU Usage is less than 1%. Use the Applications and Processes tabs to close programs if necessary.
(C) Open CPU-Z and SpeedFan. Observe CPU-Z for Intel's Speedstep to decrease Core Voltage, Core Speed and Multiplier to minimum values. Observe SpeedFan, allow 10 minute at Idle to ensure that temperatures decrease to minimums, then record Tcase Idle.
■ Tcase Idle = Ambient + Z.
"Z" compensates for Idle power dissipation and CPU cooler efficiency. Use the Scales in Section 6 to find "X" Idle Power, use the links in Section 14 to find "Y" Cooler Efficiency, use the Table and Formula below to find "Z", then add Ambient to find Tcase Idle.
■Idle Power and Cooler Efficiency Table:
X = 2 . . . Idle Power: 8W . . . . Y = 2 . . . . Cooler Efficiency: High-end
X = 3 . . . Idle Power: 12W . . . Y = 3 . . . . Cooler Efficiency: High mid-range
X = 4 . . . Idle Power: 16W . . . Y = 4 . . . . Cooler Efficiency: Mid-range
. . . . . . . . . . . . . . . . . . . . . . . . . Y = 5 . . . . Cooler Efficiency: Low mid-range
X = 6 . . . Idle Power: 24W . . . Y = 6 . . . . Cooler Efficiency: Low-end / Stock Intel
■Tcase Idle Formula:
(X + Y) / 2 = Z + Ambient = Tcase Idle.
Note 2: CPU and cooler combinations which are both lapped may subtract 1c from Tcase Idle.
Example 1: Duo
Idle Power: E2160, Stepping M0, Idle 8W, so X = 2.
Cooler Efficiency: Mid-range – Arctic Cooling Freezer 7 Pro, so Y = 4.
(2 + 4) / 2 = 3, so Z = 3.
Ambient = 22c.
3 + 22 = 25, so Tcase Idle = 25c.
Example 2: Quad
Idle Power: i7 920, Stepping C0, Idle 16W, so X = 4.
Cooler Efficiency: High-end – Xigmatek HDT-S1283, so Y = 2.
(6 + 2) / 2 = 3 so Z = 3.
Ambient = 22c.
3 + 22 = 25, so Tcase Idle = 25c.
(D) Configure Offset correction as shown in Section 11. Since the Tcase sensor was designed to be linear from Idle to Load, Tcase Load will also be accurate.
Part 2: Calibration - Tjunction Load (Uses maximum cooling at Stock Vcore, Frequency and Multiplier)
** Note 1: If BIOS does not respond properly to Stock Vcore, Frequency and Multiplier settings, then use an appropriate combination of manual settings to provide the following in CPU-Z:
Core Voltage = 1.250 V
Core Speed = Stock Mhz
(A) Start Prime95 Small FFT's. Observe CPU-Z for Intel's Speedstep to increase Core Voltage, Core Speed and Multiplier to Stock values. Observe SpeedFan. Heat saturation is typically reached within 7 to 8 minutes, so allow 10 minutes at Load to assure that temperatures increase to maximums, then record Tjunction for each Core.
■ Tjunction Load = Tcase Load + 5c.
Example 1: Duo
Tcase Load = 45c
Tjunction Load = 50c
-Tcase/Tjunction-
--45--/--50--50--
Example 2: Quad
Tcase Load = 45c
Tjunction Load = 50c
-Tcase/Tjunction-
--45--/--50--50--50--50--
(B) Configure Offset corrections as shown in Section 11.
(C) Stop Prime95, then allow the system to Idle for 10 minutes. Tjunction Idle should be ~ 4c higher than Tcase Idle.
Note 2: Tjunction sensors were designed to be linear at high temperatures for Throttle and Shutdown protection, so Tjunction Idle could indicate too low or too high. Many 45 nanometer variants have faulty sensors that "stick" and might not Idle below 50c. Sensors can be tested using Real Temp - http://www.techpowerup.com/realtemp/
■ If Tjunction Idle is not ~ 4c higher than Tcase Idle, then use Tcase Idle for accurate Idle temperature.
(D) Repeat Item (A) and allow Prime95 to run past 10 minutes while reinstalling covers. If temperatures increase, then computer case cooling should be improved.
(E) Restore the system to original or custom BIOS settings and hardware / software preferences.