Intel Core 2 Quad Q8200 Overclocking and Debunking
This article is purely in response to Tom's Hardware Q8200 overclocking attempt.
They achieve an abysmal 2.68Ghz versus the 2.33Ghz stock speed. In order to achieve this the CPU voltage was 1.4v(!) versus the stock 1.225v. They eventually knocked the Vcore down to 1.3v at the expense of setting VTT FSB Voltage to 1.4v.
These results are horrible for any CPU, let alone the notoriously overclockable Core 2. Tom's seems to have gotten a particularly bad CPU or motherboard.
I don't believe this is incompetence. However, they do posit that this result is not unusual for this chip from their research.
A Better Q8200 Overclock
My sample was able to hit 3.20Ghz without any voltage changes. Near 500FSB (3.50Ghz for the Q8200) overclocking gets difficult. The Intel P45 chipset seems reluctant to go much higher, because CPU Vcore is still below 1.3v at this point. This is an expected limitation; any processor seems to have trouble getting above 500Mhz FSB on the P45.
The highest non-insane voltage overclock I've proven stable is 3.40Ghz. This is lower than the 3.6Ghz most get with a Q6600, but still respectable.
I have not tweaked this result; it was more of a brute force attempt. I'm sure the memory timings could be brought down a bit, and possibly MCH voltage.
Hardware, Settings, and Validation at 3.4Ghz
- Intel Core 2 Quad Q8200 2.33Ghz M1 @ 3.40Ghz
- SunBeamTech Core-Contact-Cooler 120mm CPU HSF
- GigaByte GA-EP45-UD3R Motherboard @ 486Mhz FSB
- Extra 40mm Fan on Northbridge
- 2x 2GB DDR2 OCZ Reaper HPC 1066 2.1v @ 486Mhz
- ATI Radeon 4850 512MB built by Sapphire
- Antec NeoHE 430watt Power Supply
- 2x 160GB Seagate 7200.7 HDD
BIOS settings for 3.40Ghz are below. Keep in mind feature names may vary between motherboard manufacturers.
- FSB 486Mhz
- CPU Multiplier 7.0 (Stock)
- Load Line Calibration ON
- CPU Vcore 1.250v (1.225 Stock)
- MCH Voltage 1.3v (1.1v Stock)
- Memory Divider 1:1
- Memory Voltage 2.1v (Stock)
- Memory Timing 6-6-6-16 (5-5-5-15 Stock)
I've settled on a 24/7 overclock of 3.00Ghz. This is a good compromise of speed and heat for my cooling and ambient temperature. I have Load Line Calibration turned on, but no voltage or other setting changes.
Although the sun is setting on the Core 2 microarchitecture they are still a viable choice, especially for someone on a budget.
I hope this has vindicated the Q8200's poor overclocking from Tom's Hardware.
Kevin Castor Jul. 31st 2009 firstname.lastname@example.org
Donutey, since July 2005