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OCing Core2 Duo E8500 on ASUS P5B vanilla with maxed RAM


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Recently, a friend of mine decided to give me his old machine, so I've taken the opportunity to make a few upgrades to my desktop. I swapped my old Pentium Dual Core E6300 for a Core 2 Duo E8500, and my 512MB GDDR3 Radeon HD4650 for a 1GB GDDR5 Radeon HD5770, as well as adding an additional 4GB of RAM. Even though the board from my friend's machine was newer, I decided to stick with my old P5B vanilla since the newer board had only two RAM slots, as well as way fewer overclocking options (not even vcore control!).

Now, I've managed to put a pretty good overclock on this CPU, but I haven't managed to get it as far as the Pentium. I was able to push the Pentium to 3.98GHz, with the RAM, 4GB of Corsair XMS2 DDR2 clocked at 945MHz. I don't remember the exact RAM timings I used, or the voltages I had assigned.

Currently, I have my CPU running at 3.74GHz. My RAM consists of 4GB of Corsair XMS2, and 4GB of some random Kingston PC2-6400. I only have the ram clocked at 784MHz, but with really tight timings. If I go any further than these speeds, I start experiencing errors in Mprime, the Linux counterpart of Prime95. It doesn't matter if I loosen up the RAM timings or crank the voltages up, the buck seems to stop here.

Now, I know that P965-based boards struggle with having 8GB of memory installed, and they also struggle with 45nm chips, but I wonder if ANYONE would know how I can squeeze a little more horsepower out of my setup, preferably without downgrading anything. I'm big on console emulation, and I like being able to run resource-intensive emulators like the BSNES accuracy core on RetroArch, and Dolphin. Unfortunately, these two programs aren't compiled to work with XP x64, so I have to run them on Linux, which requires more power than they should need. Back when I had my previous hardware, and I was running Zorin OS 8 Gaming, I used to be able to run BSNES accuracy fine, so I don't understand why it would struggle with my current hardware and Xubuntu 14.04. It could be my video driver, as neither of the two fglrx drivers, nor the open source driver provide any decent performance.

For reference, here's my jumperfree config from the BIOS:


AI Tuning: Manual

CPU Frequency: 392 <--- I believe this is the base FSB

DRAM Frequency: DDR2-784MHz <--- I have it set to run as PC2-5300
PCI Express Frequency: Auto

PCI Clock Synchronization Mode: 33.33MHz

Spread Spectrum: Disabled

Memory Voltage: 1.95v

CPU Vcore Voltage: 1.1500V <--- Actually runs a bit lower than this due to vdroop; I tried the pencil mod for it but it didn't really work

FSB Termination Voltage: 1.300V

NB Vcore: 1.55V

SB Vcore (SATA, PCIE): 1.50V

ICH Chipset Voltage: Auto


Here's my CPU config:


CPU Ratio Setting: 09.5 <--- this is the max

C1E Support: Disabled

Max CPUID Value Limit: Disabled

Vanderpool Technology: Enabled <--- This is the old name for Intel's virtualization tech; allegedly you can increase performance by turning it off, but I leave it on so I can use VirtualBox and VMWare Player.

CPU TM Function: Disabled

Execute Disable Bit: Enabled


And finally, here's my memory/northbridge config:

Memory Remap Feature: Enabled

Configure Ram Timing by SPD: Disabled

DRAM CAS# Latency: 4

DRAM RAS# to CAS# Delay:4

DRAM RAS# Precharge: 3

DRAM RAS# Activate to Precharge: 11

DRAM Write Recovery Time: 6



Rank Write to Read Delay: 10

Read to Precharge Delay: 10

Write to Precharge Delay: 11

Static Read Control: Faster

Initiate Graphic Adapter: PEG/PCI

PEG Force x1: Disabled


I hope that's enough information. ;) I've been wracking my brain trying to push this machine further, because I know I have it at the bleeding edge. I should probably just buy a new PC, or at least a new mobo, but I'm broke, and I need to figure out how to get more out of what I have.

Edited by mrbigmouth502
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  • 2 weeks later...

" ... because I know I have it at the bleeding edge."  :yes: 


There isn't much more that you can do with that setup, if at all. The problem is the FSB. The Pentium might go a little further due to the multiplier but you will have to settle with less cache; in other words, you won't win there.


If you are looking for another mobo and a CPU in the future, check out the Pentium G3258, best single threat performance for the price as it's basically half an i5 k (both are unlocked). The G3258 can be OCed even on a cheap H61 mobo... I know, you said you are short on cash ;).

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  • 2 weeks later...

FSB termination voltage likely higher than required on a 45 nm dual core!  I doubt you need more than 1.25 V.


An FSB termination voltage bump is usually only required on Quads, because of an architecture limitation that causes interference with 4 cores.


A bus error (appears as a "STOP: 0x00000124" BSOD with "bus/interconnect error" reported in the event log) is likely when multitasking on a Quad which OTOH, is usually non-existent on a dual core. 


A 65nm Quad likely requires 1.3 V for the minimum FSB termination voltage with a small FSB OC! 


Was being a pain at just 367 Mhz, which is nothing for my P45! My 3.3 Ghz Kentsfield OC required the FSB termination voltage raised to 1.3 V and the Vcore at 1.40 V. (367x9.0)



On a P45, a Duo easily goes to 450 Mhz FSB without touching any bus or northbridge voltages. (On an E8400)

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On a P45, a Duo easily goes to 450 Mhz FSB without touching any bus or northbridge voltages. (On an E8400)


A P45 can do a 400MHz FSB (1600MHz Quad pumped) so those 12.5% over that speed would indeed be less of a problem. But a P965 is rated for a 266MHz FSB (1066) and he has it at 392 (1568); that´s 47.1% over the specs :).

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I didn't make extensive trials on my E8600+P45 (Ga-ep45-ud3r) but

- The E8600 (I bought from a manuf lot known for o'c) runs at 4GHz without any overvoltage nor tweaking

- With the P45, I concluded that the Ram bus frequency was the limit, not the Fsb (Cpu bus frequency), and the Ram latency settings have very little influence on the performance of this computer.

Edited by pointertovoid
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  • 6 months later...

The Core 2 Duo E8000 line are great CPU's that hold up well even today. I have two of them, an E8300 and an E8400 in two Inspiron 530's I have. They are more durable than Quad Core's, which I've heard tons of stories of them burning out. And what sets the E8K line apart from the other Core 2 Duo CPU's, other than the speed, is the integrated features on them. That may not mean a lot to some people, but it's HUGE to me. They not only have VT-x, known as hardware virtualization that applies to memory isolation. But also VT-d, which is for I/O (CPU isolation) and lends a huge hardware/speed assist along with security for running VM's. Not only do no other Core2Duo's have this feature, but even many Core i3 & i5 CPU's lack it. And I actually think it's more important than EPT (extended page tables).

And they also have Trusted Execution Technology, which again even most i3's & i5's lack. And this feature is necessary to utilize TPM.

i7's have it all though... and the kitchen sink. But Core 2 Duo E8K CPU's are IMO the best pound for pound so to speak processors, and were ahead of their time when new.

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