745, CPU upgrade to Xeon

the Optiplex 745 has an Intel Q965 chipset which supports the following CPUs:

http://www.cpu-upgrade.com/mb-Intel_(chipsets)/Q965_Express.html

the highest rated CPU I can see that was validated by Dell was the E6600. There were never any quad core CPUs tested by Dell so I can't say whether the CPUs you mention would work or not. 

You can find all the available BIOS updates here:

http://downloads.dell.com/published/pages/optiplex-745.html

There are physical as well as pin configuration barriers.

There is also no guarantee that the Bios has the correct microcode.

LGA 771 is not interchangeable with LGA 775.

So out of the box no this isnt working.

https://www.youtube.com/watch?v=OM4Wib9lYeA

I am install Xeon E5450 on my Asus P5Q turbo. Its work fine. But I doubt the performance with Q965 chipset.

I hoped that someone had time to test, but in the compatibility table on the link above this did not see. very sorry.

Only 65nm xeons would work because of the q965 chipset 

Intel® Xeon® Processor L5408 is 45NM!

A moded bios also known as "Sovem's SLIC 2.1 bios" will need to be flashed.

https://www.sendspace.com/file/ft3lvy

I have a Dell Optiplex 745 ussf, does it work on this model?

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@elpro999dell wrote:

Only 65nm xeons would work because of the q965 chipset 

Intel® Xeon® Processor L5408 is 45NM!

A moded bios also known as "Sovem's SLIC 2.1 bios" will need to be flashed.

https://www.sendspace.com/file/ft3lvy

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There are physical Barriers to this working in addition to the bios needing an unsupported modification.  This is beyond bad advice to presume that everything will work with a water chicken install.  It does not.

https://www.amazon.com/Intel-CPU-Socket-771-775-Sticker/dp/B00RJHM9CE

https://www.youtube.com/watch?v=Hu19kHDL8oo

https://ark.intel.com/products/33083/Intel-Xeon-Processor-E5450-12M-Cache-3_00-GHz-1333-MHz-FSB

SOCKET 771 is not drop in for SOCKET 775.

https://www.youtube.com/watch?v=HUqBW-kq1_0

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@speedstep wrote:

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@elpro999dell wrote:

Only 65nm xeons would work because of the q965 chipset 

Intel® Xeon® Processor L5408 is 45NM!

A moded bios also known as "Sovem's SLIC 2.1 bios" will need to be flashed.

https://www.sendspace.com/file/ft3lvy

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There are physical Barriers to this working in addition to the bios needing an unsupported modification.  This is beyond bad advice to presume that everything will work with a water chicken install.  It does not.

https://www.amazon.com/Intel-CPU-Socket-771-775-Sticker/dp/B00RJHM9CE

https://www.youtube.com/watch?v=Hu19kHDL8oo

 

https://ark.intel.com/products/33083/Intel-Xeon-Processor-E5450-12M-Cache-3_00-GHz-1333-MHz-FSB

SOCKET 771 is not drop in for SOCKET 775.

https://www.youtube.com/watch?v=HUqBW-kq1_0

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Flase the friends of the Chinese mafia would sell you a drop in unit for some models. 

https://www.ebay.com/itm/Intel-Xeon-X3363-2-83GHz-12M-1333-LGA-775-Quad-Core-CPU-Better-than-Q9550/282727022278?epid=74100378&hash=item41d3d7fec6%3Ag%3AwKoAAOSwDFBaBAJa&_sacat=0&_nkw=xeon+lga775&_from=R40&rt=nc&LH_TitleDesc=0 

*listing CPU is not for 745 only for 360 or 380 optiplex will work as a drop in unit.

I was able to upgrade my Optiplex 380 to a low voltage XEON processor, which has 12MB of cache, and runs very cool. The chipset recognizes the CPU as a XEON, and the fan barely ever comes on. Only 2 of the low voltage XEONs work, and the 3rd one I tried didn't work. The 3rd one I tried was faster than the 1st 2, but I don't remember the the actual CPU codes.