<< MGTasco,
Overclockers.com testing is not as accurate as most people think, nor is it as accurate as they think. NOt only do they call their temp measurement CPU temp and even call it a true core reading, when it clearly is not.
What it really is a heatsink-junction C/W. And it is severely undercutting manufacturer C/W. It is accurate within the scope of their reviews, but using their C/W measurements to determine DIE temp is impossible. USing their C/W to determine Heatsink-Junction Temp, fine.
Yes, there are other problems. When you're talking about an external measurement, maintaining accurate placement of the thermocouple is absolutely critical. When most of their heatsinks are in teh same .3-.4 range of numbers, making sure they are over the exact same part of the core will definately have an effect. yes, different portions of the core run hotter. And heatsinks do have some "shift" available in them, and some of them have enough leeway to shift 1/4inch either way away from the "center".
And regarding the swiftech, you can't compare swiftech readings to the other heatsinks. They drilled the thermocouple in from the side. It is farther away from the core than the other readings. And even more of a heatsink-temp and less cpu temp.
NO, i'm not saying the Swiftech is a bad heatsink. It is the damn best clip mechanism and damn good performance. Its just you can't compare that review to the others they do.
Thermocouples mounted to the core will also result in lower than full die temps, since you're not solely in contact with core. Again, if they match heatsink-thermocouple, they are roughly 50-70% of the core temp rise over ambient.
Going by AMD's Athlon MP pdf file, they suggest using the Palomino internal diode in conjunction with a heatsink thermocouple to determine DIE temp. This makes total sense since the internal diode is in the core, and in between it and heatsink thermocouple is the DIE temp. So guessing from their current testing, you're going to be looking at, wtih most heatsinks, DIE TEMPerature being 50% higher than even heatsink thermocouple readings.
Mike >>
Thanks Mike for the explanation. Just wanna clarify a few things. In overclockers.com, they say that they drill a hole through the centre of the heatsink and place the thermocouple there touching the top of the core. Is this what you consider heatsink-junction temperature?
But looking at the current situation now without any internal diode in AMD chips, wouldn't you consider that overclockers.com method would the most accurate compared to most other websites which basically just uses the mobo thermistor? I mean..yes..overclockers.com may not be accurate enough, but isn't it the closes you could get looking at the condition of AMD chips now?