Why is my Barton 2500 topping out at 2.2ghz with these temps????

[Metalloid15]

Someone please explain this to me. My system is rock stable at 2.2ghz with my vcore at 1.725v. Temps never get above 32c even after 15+ hours of Prime95. So I bump it up to 2230mhz and run Prime95 again, and it craps out after like 5 min. So I push the vcore to 1.75v and run it overnight. I woke up this morning and Prime95 was giving errors. My CPU temps were topping out at 34.5C.

I just don't understand how I can be stable at 2200 with 1.725v vcore, but I can't push it an extra 30mhz even after bumping the vcore to 1.75v. It is almost like my CPU has a ceiling on it and it just refuses to go higher than 2200. Anyone else seen similar problems?

Barton 2500 @2200 (11x200)
Abit NF7 rev 2.0
512mb Crucial PC3200
Antec TRU430 PSU
Radeon 9700 PRO
Maxtor 60gb 7200rpm
Thermalright AX-7 w/ 80cfm Delta
2x120mm 130cfm Delta's

[brennan77]

Yeah, that makes sense. It seems you've hit the point of diminishing return. As you overclock higher, it takes more and more voltage to gain smaller and smaller advantages in mhz.

For instance, I can run 1.675v at 2300mhz on my system, but it takes a solid 1.85v to run at 2400 or more.

[Metalloid15]

When I finally get my watercooling setup in (sometime between December 2003 and December 2009), will it make much of a difference? Or am I stuck at this speed?

[Twister1234]

your temps seem ok,dont think,that watercooling would make a big difference...

[hitechjb1]

If you increase the voltage slowly step by step, and recorded the stable MHz, temperature vs voltage. When it comes to getting less than 30 MHz per 100 mV Vcore increase, it reaches the wall for overclocking.

It is a result of temperature increases faster than the gain in MHz, hence slowing down the CPU.

Every CPU is different, even CPU with same stepping and date can be very different. Some reaches diminishing return at 2.2 GHz, some at 2.3 GHz, some at 2.5 GHz, sooner or later.


Originally posted by hitechjb1
General rules on voltage and temperature for CPU overclocking

Higher CPU voltage is needed to sustain higher CPU frequency. Increase the voltage gradually if needed, step by step (25 mV step in bios) so that CPU frequency can be raised. Monitor CPU stability by running Prime95, and CPU temperature during this process. Keep the temperature lowest possible using best affordable cooling. For air, SLK-800U/900U/947U plus a high CFM, variable speed fan are the best choice.

1. At early stage of overclocking, within 10% above rated voltage, overclocking is an easy, linear ride of frequency over voltage, about 100-130 MHz / 100 mV (for Tbred B/Barton).

2. Around the break-even point of overclocking, characterized by about
- 10 MHz / C of temperature increase, or
- 30 MHz / 100 mV of Vcore increase
for Tbred B/Barton. Beyond the break-even, it becomes much more difficult to overclock higher. This happens around 1.8 - 1.9 V.

3. Above the break-even point, diminishing return occurs, i.e. heat will eat into more than half of the frequency increase from the increase in power put into the CPU for sustaining higher frequency. Temperature would rise quickly and much more voltage would be needed to gain few MHz, making further overclocking very costly (high PSU current, cooling, CPU life expectancy degradation) and impractical (huge fan noise, little performance gain). Even the Vcore can be increased higher (beyond 1.9 - 2.0 V) and system is stable, there would be practically little gain in MHz (less than 30 MHz / 100 mV).

For Tbred B/Barton, the break-even point would be around 2.3 - 2.5+ GHz using the SLK- HSF mentioned earlier. Tbred B 1700+/1800+ DLT3C has a slight edge of about 100 MHz (CPU raw power) on max overclocking frequency, compared to other Tbred B/Barton (Barton has a larger L2 to tie the overall system performance though).


Voltage (estimate) needed for overclocking Tbred B and Barton

Assuming HSF, PSU are not the limiting factor, these are my estimate, based on SLK-800/900/947 HS.

For Tbred B, 1700/1800 DLT3C, in most cases, I use these numbers:
1.500 - 1.575 V would get CPU to 2200 MHz (stable) = 200 x 11
1.550 - 1.650 V would get CPU to 2300 MHz (stable) = 200 x 11.5
1.625 - 1.750 V would get CPU to 2400 MHz (stable) = 200 x 12
1.725 - 1.925 V would get CPU to 2500 MHz (stable) = 200 x 12.5
...

Extending them to Barton and DKT3C, I would say usually:
1.650 - 1.725 V would get CPU to 2200 MHz (stable) = 200 x 11
1.700 - 1.800 V would get CPU to 2300 MHz (stable) = 200 x 11.5
1.775 - 1.900 V would get CPU to 2400 MHz (stable) = 200 x 12
1.875 - 2.075 V would get CPU to 2500 MHz (stable) = 200 x 12.5
...

For the 1.6 V rated DUT3C, it would resemble the numbers for Barton/DKT3C.



Related links:

Some numbers to determine max CPU overclocking frequency - Vcore vs temperature,
When do the CPU's slow down? (http://forum.oc-forums.com/vb/showthread.php?s=&postid=2026527#post2026527) (page 13)
Explanation (http://forum.oc-forums.com/vb/showthread.php?s=&postid=2035026#post2035026) (page 13)

Overclocking frequency-Vcore break-even point for Tbred B/Barton (http://forum.oc-forums.com/vb/showthread.php?s=&postid=2197001#post2197001)(page 15)