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I have an ASUS P5N-EM HDMI motherboard. Currently, it's using an oldish P4 cpu. Works fine.

I just received a spankin' new Core2 Quad Processor Q8400 a few mins ago. Unopened, in the box.

I have no idea if this cpu will work in my motherboard. My motherboard is a Socket LGA775, though. I'm running the latest BIOS (for my mobo) which is version 4.01. That said, I don't think the CPU is listed on any documentation. I'm worried that it won't work .. and if so .. why would that be?! The mobo is around 8 months old, i think.


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up vote 2 down vote accepted

The processor probably just wasn't out when the motherboard was made, it should work fine.

CONFIRMED: It's compatible with all Core 2 Quad processors.

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El wikidio :) Cheers! I'll post back in a few days with luck/failure :) – Pure.Krome Jul 20 '09 at 23:58
Yep - works great :) I've also lapped my CPU and Heatsink and it all works :) – Pure.Krome Aug 20 '09 at 1:29

Confirmed from the ASUS page for your board:

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LGA775 Intel® Core™2 Processor Ready This motherboard supports the latest Intel® Core™2 processors in LGA775 package. It also can support Intel® next generation 45nm Multi-Core CPU.

The CPU-Upgrades list for your motherboard: ASUS P5N-EM HDMI,
last updated Mar 2, 2009, does not show Q8400, though it shows E8400.

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Here's's product page for this motherboard. It looks like you should be able to use your new CPU!

Here are the Cliff's Notes:

Supported CPU
CPU Socket Type     LGA 775
CPU Type    Core 2 Quad / Core 2 Extreme / Core 2 Duo
FSB     1333/1066MHz
Supported CPU Technologies  Hyper-Threading Technology


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