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Optiplex 745 USFF and Optiplex 755 USFF CPU upgrade problems.
Hello everyone.
My english could be better, but I hope it goes.
My problem is that I have a Dell Optiplex 745 USFF with 2.6.6 bios and a Optiplex 755 USFF with A22 bios. So they are both bios updated.
I have heard a lot about that the Dell USFF cant run Quads processors over 65W because of the external power brick on only 220W. But i thought i will give it a try, so i did buy some cheap quads (Q6600, Q8400)
First i tried the Q8400 in my Optiplex 755 USFF, but It just keep going spin up and off, spin up and off with yellow light on the power button. Then i tried the Q6600 also in my 755. it did boot up, but says: incompatible processor ..
Then I tried the Q6600 in my 745 USFF. It boot up and run great? I have not tried the Q8400 in my 745 because I know it cant run 1333MHz processor.
But why do my 745 USFF work with Q6600 when my 755 does not?
i prefer using the 755 because of higher ram and cpu speed.
Regards
beamermt79
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August 24th, 2017 10:00
Don't know the technical explanation but from the spec sheets, it looks like the quad core processors were locked out on the 755 for whatever reason. Regardless, those processors run at higher then 95W and if your system is only rated at 65W you run a high risk of damaging the motherboard.
speedstep
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August 29th, 2017 08:00
Quad Core wasn't locked out on the 755. The Q6600 and Q6700 are listed as standard. There are over 20 bios revisions however. So you need current bios and you cant jump from A01 to A22 in one step.
USFF units cannot use QUAD core because their power supply is too small.
http://www.dell.com/downloads/global/products/optix/en/opti_755_techspecs.pdf
Description
This package provides the BIOS Update for Dell OptiPlex 755 running the following Operating Systems: Windows and DOS.More details
OptiPlex 755 System BIOSMore details
This package provides the BIOS update for Dell Optiplex 755 running the following Operating Systems: Windows and DOS.More details
OptiPlex 755 System BIOSMore details
OptiPlex 755 System BIOSMore details
OptiPlex 755 System BIOSMore details
OptiPlex 755 System BIOSMore details
OptiPlex 755 System BIOSMore details
OptiPlex 755 System BIOSMore details
OptiPlex 755 System BIOSMore details
OptiPlex 755 System BIOSMore details
OptiPlex 755 System BIOSMore details
OptiPlex 755 System BIOSMore details
Dell OptiPlex 755 System BIOSMore details
Optiplex 755 BIOSMore details
Initial BIOS release.More details
beamermt79
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August 29th, 2017 11:00
They were talking about the USFF not the SFF
Anonymusen
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August 29th, 2017 14:00
My 745 USFF runs great with Q6600 processor and 2gb PC2 6400 800MHz memory.
Idle temp is 35-45ºC and under max load the temp is 70ºC so im not concerned.
I have found out that you cant count on the technical sheets from Dell. Because it also says that 745 USFF CAN'T run Quads processor and 800MHz memory speed.
But mine 745 USFF runs great with Q6600 and PC2 800MHz memory.
The technical sheets also says that 755 DT max can run 8gb memory, but mine 755 DT runs great with 16gb.
Is there somehow i can unlock the 755 USFF, so it can run Quads like the 745 USFF can?