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Subject: Re: AMD vs Pentium

Author: Aaron Gordon

Date: 21:38:31 03/17/03

Go up one level in this thread


On March 18, 2003 at 00:06:36, Robert Hyatt wrote:

>On March 17, 2003 at 22:37:33, Aaron Gordon wrote:
>
>>On March 17, 2003 at 15:26:15, Sakkas Takis wrote:
>>
>>>The AMD are geting very hot when you use chessprograms
>>>Go for Intel
>>
>>How do you figure? Look at both AMD and Intel technical documents (or test one
>>yourself). AMD's run quite a bit cooler (by some 20-30 watts).
>
>
>Just for the record, "watts dissipated" is not the same thing as "running hot or
>cool."  The Cray-3 for example radiates 125 kilowatts.  Yes, that is kilowatts.
>It runs about -70C or so, immersed in liquid.  A chip can convert more watts to
>heat, but _still_ run cooler if it has a solid path for the heat to escape
>quickly (as does the Cray with copper rods and plates everywhere).
>
>That is the limiting factor on speed, in fact.  Ramp up the voltage to ramp up
>the clock and eventually you reach the point where the heat can't get out as
>quickly as it builds up, and the thing melts.

If you have the exact same cooler (lets say 0.15 c/w) with the exact same
thermal compound (Arctic silver 3 for example) then more watts means more heat.

I'm going to round down the P4 to 100 watts (I think it's closer to 110 watts).
Anyway. A cooler with a 0.15 c/w rating and a 27c ambient temperature would keep
the P4 at 42C. Now, lets try that with an AthlonXP 2800+ (rounding to 75 watts).
39C cpu temp.

As long as the cooling remains the same P4's are going to run hotter. No doubt
about that. More watts means more heat. Doesn't matter if you're putting a
cooling block on the core thats room temp or absolute zero. Heat is heat.
1 watt > 2 watts.

Lets try a 'normal' heatsink/fan c/w rating. Say, 0.35c/w. 27C ambient, 100 watt
cpu, thats 62C full load. Pretty toasty. Lets try that with an AthlonXP 2800+...
27C ambient, 53.25C full load. I wouldn't mind my cpu at 53C but 62C is really
pushing it.

Just for the fun of it lets throw in my particular setup. AthlonXP 2512MHz,
1.98v, 137.849 watts. If you think THAT is hot.. you should see my friends 200
watt P4 @ 4GHz. Anyway, 15C ambient air temp on average, 16C water temp, liquid
cooler c/w is 0.0766c/w and the cpu temp is 26.56C full load. :)



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