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Thermal Conditions and Overclocking

The thermal conditions of the new Prescott processor core is a very “hot” topic. When Intel engineers developed the processor, they faced a problem of high leakage currents, which lead to excessive power consumption and high heat dissipation. Although Prescott based processors are manufactured with more advanced production technology and feature lower Vcore, Intel still had to update the power requirements to mainboards and CPU voltage regulator circuitry – Prescott FMB 1.5. Moreover, the CPUs working at over 3.4 GHz frequencies are incompatible with the today’s mainboards exactly for this particular reason: high power consumption.

At the same time Intel claims that Prescott CPUs with the working frequencies below 3.4GHz will be compatible with all Socket 478 mainboards supporting top Pentium 4 (Northwood) processors today. The only thing the mainboard guys should do, is to update the BIOS of their solutions to make sure that it recognized the CPU correctly. As for the coolers for the new Prescott processors, there are no specific requirements here.

Nevertheless, Prescott based CPUs dissipate more heat than Northwood based ones. For instance, you can take a look at the table below, with the TDP values (Thermal Design Power) for Northwood and Prescott, and also Pentium 4 Extreme Edition:

 

Pentium 4 (Prescott)

Pentium 4 (Northwood)

Pentium 4 Extreme Edition

Vcore

1.25-1.4V

1.475-1.55V

1.475-1.55V

3.4GHz

103W

?

?

3.2GHz

103W

82W

92.1W

3.0GHz

89W

81.9W

-

2.8GHz

89W

69.7W

-

As we see, the current Prescott revision is already the third one, and the previous two were canceled exactly because of the too high heat dissipation. However, the mass Prescott based CPUs are really a way too “hot” even compared with the Pentium 4 Extreme Edition, which consist of more transistors. This way, the thermal conditions inside Prescott based systems promises to become much more severe.

However, let’s take a look at the practical aspect of this matter. We measured the actual temperatures of Pentium 4 Prescott, Pentium 4 Northwood and Pentium 4 Extreme Edition working at 3.2GHz. For our tests we used the same cooler taken from the boxed supply (the boxed versions of all the three CPUs come with one and the same cooler. The temperatures were measured according to the built-in on-die thermal diode.

We measured the minimal CPU temperature in idle mode and maximum CPU temperature in burn mode, when the CPU was warmed up with the help of special utilities:

 

Idle

Burn

Pentium 4 (Prescott) 3.2GHz

45oC

61oC

Pentium 4 (Northwood) 3.2GHz

30oC

48oC

Pentium 4 Extreme Edition 3.2GHz

32oC

51oC

I don’t think I need to comment on these numbers. Prescott processors warm up much more during active work than their predecessors. Note that we measured the CPU performance during the tests carried out in an open testbed. I am scared to imagine what happens to Prescott when we close the system case…

As a result, there is no doubt that Prescott is the warmest x86 processor today. When you purchase a system based on this CPU, you should always keep in mind this fact. Moreover, Intel introduced new requirements for case manufacturers and system builders. The main idea of these requirements implies that they have to provide low air temperature in the CPU area. On our part, we can only agree that you should pay special attention to thermal issues and proper cooling of your system and your CPU when working with a Prescott based system.

 
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