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The Pentium
E6500 (2MB Cache) is a variant of the
E7500 (3MB Cache), which are both related to the
E8400 (6MB Cache). All are Core 2 Duo 45 nanometer 65 Watt TDP processors. Aside from differences in Cache and FSB (Front Side Bus) frequency, these processors are essentially identical. These Core 2 erra processors predate Core i 1st generation processors, as well as "Z" series motherboards that support Core i 2nd generation and later processors.
Alex3200,
If there's a later version of BIOS available, and you're comfortable with the flash procedure, then go ahead and flash your BIOS. As you might already know, overclocking on the
Asus P5KPL-AM-SE motherboard is done by increasing FSB frequency on the G31 Northbridge chipset,
if BIOS allows.
Your motherboard supports up to Core 2 Quad Q9xxx CPUs, and its G31 chipset supports 800, 1066, 1333 and 1600MHz memory. Since your E6500 defaults to 266MHz FSB with an 11 multiplier, 266MHZ x 11 = 2.93GHz. By increasing the FSB to 333MHz, the 11 multiplier gives you 3.66GHz, which typically should
not need an increase in Vcore.
However, if you already have instabilities, then overclocking will make the problem more severe. Keep in mind that as you increase FSB frequency to overclock the
CPU, this also overclocks the
memory which can cause instabilities. This may require you to choose a different "strap" to decrease the FSB / memory ratio, which in turn decreases memory frequency, thereby restoring memory stability.
If your rig is table at stock, then your memory is also at stock, which always runs at FSB x 4. So 266 x 4 = 1066. If the FSB is increased to 333, then the
CPU is at x 11 which is 3.66GHz, but 333 FSB x 4 overclocks the
memory to 1333, which is typically too fast for 1066 memory to remain stable. If you keep the memory strap at 266, then the memory will run at 1066MHz. Increasing memory voltage and / or relaxing timings may stabilize higher frequencies, just as tightening timings will improve latency at lower frequencies.
Here's some examples that compare stock settings to different CPU / memory clock combinations:
CPU 11 x 266 =
2.93, RAM 4 x 266 =
1066 (CPU & RAM stock- FSB 266, strap 266)
CPU 11 x 291 =
3.20, RAM 4 x 291 =
1164 (RAM marginal - FSB 291, strap 266)
CPU 11 x 309 =
3.40 , RAM 4 x 232 =
928 (RAM underclock - FSB 309, strap 200)
CPU 11 x 318 =
3.50 , RAM 4 x 239 =
956 (RAM underclock - FSB 318, strap 200)
CPU 11 x 333 =
3.66, RAM 4 x 333 =
1333 (RAM unstable - FSB 333, strap 333)
CPU 11 x 333 = 3.66, RAM 4 x 266 = 1066 (RAM stock - FSB 333, strap 266)
CPU 11 x 346 =
3.80, RAM 4 x 276 =
1105 (CPU & RAM marginal - FSB 346, strap 266)
3.66GHz option underlined above is a 25% overclock with a corresponding increase in CPU performance, which is certainly enough to notice. The 3.66GHz overclock is the easiest option because it avoids having to tweak memory timings and / or voltage. It should
not require any increases in Vcore, and does
not compromise stock memory stability or performance. Whatever options you can tweak after flashing BIOS, do not exceed 80°C or 1.375 Vcore.
There are overclocking guides still available for 45 nanometer Core 2 processors, so Google around the web. You might even find one that covers similar motherboard / CPU combinations. If done correctly, you should be able to achieve an overclock of at least 3.66GHz. 45 nanometer Core 2 processors are capable of reaching 4.0GHz and more. A 40% overclock is not uncommon.
CT