64 bit upgrade for dell 8400

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May 31, 2010
What is required to upgrade the following to use 64 bit os/software

System Manufacturer Dell Inc.
System Model Dimension 8400
System Type X86-based PC
Processor Intel(R) Pentium(R) 4 CPU 3.40GHz, 3391 Mhz, 1 Core(s), 1 Logical Processor(s)
BIOS Version/Date Dell Inc. A03, 10/11/2004
SMBIOS Version 2.3


Jun 15, 2007
Just a word of warning Adrian, the Dell Dimension 8400 does not properly support 64-bit operating systems.

What I mean is that you will not find the drivers for 64-bit operating systems on Dells website for that model.


Sep 2, 2010
I don't think they are right. I have been looking into putting a 64 bit os on my 8400 and from what I have seen you can do and others already have. A lot of plps answer to everything on here is buy new this and then upgrade that. LAZY.

No you can't. It is a 32 bit processor.


Sep 5, 2010
I put Window 7 64-bit Ultimate on my Dell 8400 two days ago and I am sooooooo glad I did. I have a P4 HT @ 3.0ghz and it supports 32-bit AND 64-bit so yours may very well do the same as it is a better CPU. Here is how to find out.

Download Everest Ultimate (its free to try)
After you run it on the left hand side of the display go to
Motherboard > CPU
Under the heading "Instruction set" look for "x86-64"
If its there your good to go!

Next update your BIOS to at least version A09
(Update all of your drivers etc. anyway, even if you don't decide to upgrade to 7)

Also did you run the Windows Upgrade Adviser?
If not, do that.

So you want to upgrade just to see if Windows 7 64-bit works, without out getting rid of your current OS and being able to go back to your original OS if Windows 7 won't run on your 8400?

For free?

If all of that checks out go here....


Then here....


And finally here....


I did it and it was effortless.

After 7 is up and running

Run the windows loader.

Finally install the driver for whatever adapter you use to connect to the internet (It needs to be the 64-bit version remember? If its common enough it will be on the windows cd)

You can download it in your 32-bit OS before you install the 64 bit and still access it from inside Win 7 once its up and running.
Sometimes 7 can even run it in compatibility mode.

Its not as complicated as it sounds.

Connect to the internet.

Now run windows update and it should install any missing drivers etc.
It is pretty good about finding them.

The End

This is all just for the purpose of seeing if you CAN run Windows 7 64-bit.
Now, of course, you should then uninstall it after you determine if you want to keep Windows 7 or not, then go spend
the $270.00 on a store bought copy instead .................

I sure as hell wished someone would have done for me what I just did for you.

This is what I got from this forum instead of any help, just vile, nasty people. Warning don't read this if you just ate.


I posted on another thread about upgrading the 8400, you should check it out.

Scroll down to the bottom and read my post, the Motherboard I recommend is awesome for upgrading the Dell 8400.

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