• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

Overclocking Escapades: Intel socket LGA775 Core 2 Quad Q8400 SLGT6

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.

Tech Tweaker

Dec 14, 2010
Tested out another LGA775 Quad.

Really surprised by how easily this CPU overclocked. I was at a 1.1GHz overclock (3.7GHz, stock 2.66GHz) and I was below the stock VID of 1.2875v (I was at 1.248v). This thing might be golden, in my opinion. The only reason I stopped at 3.8GHz was because I couldn't get the system stable at higher Front Side Bus speeds, and I'm fairly certain that this CPU has more to give. It might be able to hit 4GHz with the right board. And temps with a 1.2GHz overclock are really quite reasonable, 53°C max during testing is really mild for a Core 2 Quad (in my opinion) (and it would be lower during normal system loads such as gaming, internet browsing, or sending/receiving emails).

This CPU overclocks higher than my Q6600, requires less voltage to remain stable at said speed, and uses less power (watts) overall from the system. Wish I'd swapped this CPU into my backup PC back when it was my main PC, would have likely made my computing experience a more pleasurable one.

CPU: Core 2 Quad Q8400
Motherboards: Gigabyte GA-EP45-UD3P/Gigabyte GA-G33M-DS2R
RAM: 2x1GB Crucial Ballistix .16FD3 Micron D9/4x2GB G.Skill F2-8500CL5D-4GBPK x2
SSD/HDD: OCZ Agility 3 60GB/Western Digital Caviar Blue 320GB
PSU's: Corsair TX750/Corsair HX750
Cooling: Cooler Master Nepton 280L/Corsair H80

Intel Core 2 Quad Q8400 overclock settings
VID: 1.2875v (date code: L000)
2.66GHz (333x8) (stock): 1.12V (1.15V) (idle: 28-35-37-37) (load: 41-35-40-38) -GA-EP45-UD3P
2.7GHz (338x8): 1.12v (1.15v) (idle: 28-35-37-37) (load: 40-35-39-38) -GA-EP45-UD3P
2.8GHz (350x8): 1.12v (1.15v) (idle: 28-35-37-37) (load: 40-35-39-38) -GA-EP45-UD3P
2.9GHz (363x8): 1.12v (1.15v) (idle: 25-35-37-37) (load: 43-35-42-40) -GA-EP45-UD3P
3GHz (375x8): 1.12v (1.15v) (idle: 28-35-37-37) (load: 43-36-42-41) -GA-EP45-UD3P
3.1GHz (388x8): 1.12v (1.15v) (idle: 26-35-37-37) (load: 46-39-45-43) -GA-EP45-UD3P
3.2GHz (400x8): 1.12v (1.15v) (idle: 27-35-37-37) (load: 44-37-42-41) -GA-EP45-UD3P
3.3GHz (413x8): 1.152v (1.175v) (idle: 28-35-37-37) (load: 44-37-43-42) -GA-EP45-UD3P
3.4GHz (425x8): 1.168v (1.2v) (idle: 26-35-37-37) (load: 43-36-42-42) -GA-EP45-UD3P
3.5GHz (438x8): 1.2v (1.225v) (idle: 29-35-37-37) (load: 47-40-45-44) -GA-EP45-UD3P
3.6GHz (450x8): 1.216v (1.25v) (idle: 28-35-37-37) (load: 48-41-47-46) -GA-EP45-UD3P
3.7GHz (463x8): 1.248v (1.275v) (idle: 29-35-37-37) (load: 51-43-49-48) -GA-EP45-UD3P/1.248-1.296v (1.325v) -GA-G33M-DS2R
3.8GHz (475x8): 1.312v (1.3375v) (idle: 28-35-37-37) (load: 53-46-51-50) -GA-EP45-UD3P
Last edited:


Aug 10, 2016
Charlotte, NC
Thanks for the post on this topic! I have both of those chipsets as well (Q6600 and Q8400) I haven't messed with the Q8400 yet but you have me thinking that maybe I need to shift my focus before I get too far into the Q6600. Our builds look very similar as well. I will stay subbed to this thread and hopefully we can get some good info.


Jan 18, 2012
The LGA 775 boards in general seem to have long legs. I just pulled one out of the closet and decided to bring it out of retirement. A few days of tweaking, a cheap CPU upgrade and I have a respectable gaming rig. The big thing I noticed was cranking up the PCIe bus by 10MHz (settled at 9MHz for stability) made a huge difference in performance. I have the q9650 running at 3.7GHz with the PCIe bus at 109MHz. I now have the box putting up good PassMark scores for an overall 2610 score which is plenty for gaming at high resolution. I don't think it would make sense to build one from scratch but if you have an old LGA775 box sitting around and spend some time working with it, it's worth dropping a few dollars into a graphics card and some memory. I kind of view this like hotrodding an old Mustang or Camaro, no it's not as good or as fast as a new car but it's still a worth while endeavor. Now back to WoT.