pwnt by pat said:
What is the maxium volts that can be run through the chip with any kind of cooling. That sandbox post has been more than helpful but it confuses me for the most part. AMD specs say that its 2.03 however in the database there are chips with higher voltage. I see most people don't run over 1.875 so what's concidered safe before frying the cpu?
There is not a single number that can fit your question.
CPU voltage: from stock to max absolute, from efficient overclocking to diminishing return
1. For Tbred B/Barton, the
default voltage ratings (stock voltage) are
- For mobile Barton, 1.45 V
- DLT3C 1.5 V
- DUT3C 1.6 V
- DKT3C 1.65 V
This is the default voltage rating AMD recommends to use.
2. The
max absolute voltages that AMD put up are:
Quoted from AMD:
"The AMD Athlon XP processor model 8 should not be subjected to conditions exceeding the absolute ratings, as such conditions can adversely affect long-term reliability or result in functional damage."
- For DLT3C, e.g. 1700+ DLT3C
Vcc_core_dc_max = 1.5 + 0.05 = 1.55 V
The
absolute rating for Vcore = 1.55 + 0.5 = 2.05 V
- For DUT3C, e.g. 1700+ DUT3C, 2100+
Vcc_core_dc_max = 1.6 + 0.05 = 1.65 V
The
absolute rating for Vcore = 1.65 + 0.5 = 2.15 V
- For DKT3C and Barton, e.g. 2500+, 3200+
Vcc_core_dc_max = 1.65 + 0.05 = 1.70 V
The
absolute rating for Vcore = 1.70 + 0.5 = 2.20 V
Ref:
Max Vcore for Tbred B and Barton (page 5)
How much voltage can be applied to a CPU (page 5)
3. For overclocking, the
"efficient overclocking voltage" that gives the most overclocking frequency and keeps temperature below diminishing return is
- between 1.5 to 1.85 V for DLT3C and mobile Barton,
- between 1.6 to 1.95 V for DKT3C and desktop Barton
getting about 100 - 130 MHz per 100 mV.
Ref:
General rules on voltage and temperature for CPU overclocking (page 16)
4. If one needs to get the last MHz (last stable 100 MHz) from the CPU, then the CPU has to operate above the "efficient overclocking voltage" and below the "max absolute voltage" . The CPU would have to operate in the
diminishing return regime in which every mV of voltage added to speed up the CPU frequency would be counter-acted by the heat increase which in turn slow down the CPU. The return of MHz from voltage is small (< 30 MHz per 100 mV, < 10 MHz / C) and is costly in term of cooling, power supply in this operating range.
This voltage range is recommended for benchmark testing and competition, and not necessary for 24/7 usage. If one has only a CPU to rely on, don't operate it constantly in this voltage range.
Ref:
Some numbers to determine max CPU overclocking frequency - Vcore vs temperature,
When do the CPU's slow down? (page 13)
Explanation (page 13)
5. The effect of high voltage on
CPU life expectancy is discussed in:
How to determine "highest" voltage and temperature for CPU overclocking (page 16)
Effect of high Vcore and electromigration on CPU failure time (page 15)
Effect of high Vcore and electromigration on expected failure time for Tbred B/Barton (page 15)
What is gate break-down voltage (page 16)
Related links:
Relationship of clock, die temperature and voltage (update)
- What is the active power of a CPU at frequency f and voltage V
- How to estimate CPU static and active power
- Effect of die temperature on CPU clock frequency at a given Vcore
(page 13)
Vcore vs processor frequency and cycle time (page 19)
Why frequency and voltage are important for overclocking performance (page 19)