OptiPlex 755 CPU Upgrades

Question

I am looking to upgrade the CPU in my OptiPlex 755 (Service Tag <ADMIN NOTE: Service tag removed per privacy policy>) to a Core 2 Quad. Originally I purchased a Q9650 but the vendor sent me a QX9650 (Extreme) because they were out of the Q9650. I found that the Extreme Edition does NOT work in my computer, even with the latest BIOS update. In my search of these forums I confirmed that the QX9650 isn't supported, however the Q9650 and Q9550 are. I will receive my Q9550 tomorrow and want to be sure that my system will, in fact, support the Q9550. I have seen that the OptiPlex 760MT was shipped with two different motherboards, one supporting only dual core and the other supporting quad core. Is this the case with the 755 as well? Any information is greatly appreciated!

speedstep · Accepted Answer

I always recommend updating the BIOS with Antivirus software REMOVED Before updating CPU.

Compatible Processors

Intel® Core™2 Quad Processor Q9650 (12M Cache, 3.00 GHz, 1333 MHz FSB)

Intel® Core™2 Quad Processor Q9550S (12M Cache, 2.83 GHz, 1333 MHz FSB)

Intel® Core™2 Quad Processor Q9550 (12M Cache, 2.83 GHz, 1333 MHz FSB)

Intel® Core™2 Quad Processor Q8400S (4M Cache, 2.66 GHz, 1333 MHz FSB)

Intel® Core™2 Quad Processor Q9400 (6M Cache, 2.66 GHz, 1333 MHz FSB)

Intel® Core™2 Quad Processor Q8400 (4M Cache, 2.66 GHz, 1333 MHz FSB

Intel® Core™2 Quad Processor Q9300 (6M Cache, 2.50 GHz, 1333 MHz FSB)

Intel® Core™2 Quad Processor Q8300 (4M Cache, 2.50 GHz, 1333 MHz FSB)

Intel® Core™2 Quad Processor Q8200S (4M Cache, 2.33 GHz, 1333 MHz FSB)

Intel® Core™2 Quad Processor Q8200 (4M Cache, 2.33 GHz, 1333 MHz FSB)

Intel® Core™2 Duo Processor E8600 (6M Cache, 3.33 GHz, 1333 MHz FSB)

Intel® Core™2 Duo Processor E8500 (6M Cache, 3.16 GHz, 1333 MHz FSB)

Intel® Core™2 Duo Processor E8400 (6M Cache, 3.00 GHz, 1333 MHz FSB)

Intel® Core™2 Duo Processor E6850 (4M Cache, 3.00 GHz, 1333 MHz FSB)

Intel® Core™2 Duo Processor E6750 (4M Cache, 2.66 GHz, 1333 MHz FSB)

Intel® Core™2 Duo Processor E6540 (4M Cache, 2.33 GHz, 1333 MHz FSB)

Intel® Core™2 Duo Processor E6550 (4M Cache, 2.33 GHz, 1333 MHz FSB)

Intel® Core™2 Duo Processor E7600 (3M Cache, 3.06 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E6600 (4M Cache, 2.40 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E6400 (2M Cache, 2.13 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E7500 (3M Cache, 2.93 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E7400 (3M Cache, 2.80 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E7300 (3M Cache, 2.66 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E6700 (4M Cache, 2.66 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E7200 (3M Cache, 2.53 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E4700 (2M Cache, 2.60 GHz, 800 MHz FSB)

Intel® Core™2 Duo Processor E4600 (2M Cache, 2.40 GHz, 800 MHz FSB)

Intel® Core™2 Duo Processor E4500 (2M Cache, 2.20 GHz, 800 MHz FSB)

Intel® Core™2 Duo Processor E6420 (4M Cache, 2.13 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E4400 (2M Cache, 2.00 GHz, 800 MHz FSB)

Intel® Core™2 Duo Processor E6320 (4M Cache, 1.86 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E6300 (2M Cache, 1.86 GHz, 1066 MHz FSB)

Intel® Core™2 Duo Processor E4300 (2M Cache, 1.80 GHz, 800 MHz FSB)

DELL-Chinmay S · Answer

Hi RJGill84,

I would request you to edit the post and remove the Service Tag. Do not post any personal information on the community forum for security reasons.

Optiplex 755 has following variants:

USFF Chassis
SFF Chassis
DT Chassis
MT Chassis

You can check the technical specifications for all the variants from the link: http://dell.to/UXdcUj The OptiPlex 755 supports the Intel Core2 Quad, Intel Core2 Duo, Intel Pentium dual-core, Intel Celeron processors based on Intel's 775-pin (LGA775) socket. You can find the list of processors tested by Dell in an image below:

(Click on image for enlarged view)

Your computer is shipped with 275W power supply. The max TDP for the processor Q9550 is 95W and the FSB is 1333 Mhz. So Q9550 might work on your computer. You can check the comparison for the processors Q9550, Q9650 and QX9650 from the link:http://intel.ly/Tg3g6m You can also refer to the link: http://dell.to/UFnC8Q

Processor is not a customer replaceable unit as it requires lot of technical expertise. Still if you like to replace it on your own, you can find detailed information on replacing processor from link: http://dell.to/Z4S036

Dell does not offer processor or motherboard upgrades for purchase as discrete items, nor does Dell recommend upgrading the processor or motherboard in any given system. Therefore, Dell cannot support systems in which the motherboard or processor has been upgraded through third-party services or products. For more information, you can refer to the link: http://dell.to/TXOJja

Please reply for further clarifications.

speedstep · Answer

Yes Update to A21. Make sure you dont have any antivirus software running when you do that.

Description	Importance	Version	Released	Supported OS	Download
DELL,DSK PROG,BIOS,OPTI-755,,A21 OptiPlex 755 System BIOS	Recommended	A21	12/23/2011	BIOS
Dell OptiPlex 755 System BIOS, A19 OptiPlex 755 System BIOS	Recommended	A19	6/30/2011	BIOS

RJGill84 · Answer

Great! Thanks for the info guys! Should I update the BIOS with the latest (A21) version for the 755 series or the one that comes up under my service tag (A19)?

BigD... · Answer

So I have a couple of these 755 SFF units, with E4500 and 2gb pc2-5300 ram. I am considering upgrading to e8400's and 8gb of pc2-6400 ram. One machine will be used for virtualization and one as file server. Is this a logical investment? Both machines have the ATI 2400 pro graphics cards also. I assume the A21 BIOS update is also the logical choice? Thanks, D

BigD... · Answer

Yes, 4 slots. Thanks!

speedstep · Answer

If your system has 4 ram slots you can upgrade to 8 gig DDR2.  If it has 2 Ram slots then 4 Gig is max. Bios update is also recommended when trying to upgrade ram.

efremmc2 · Answer

I upgraded the power supply to a 600W (Thermaltake TR2 600W) and installed the EVGA GeForce 640 GT successfully. The card length is less than 6in. The upgraded system was a Dell 755 MT. Replaced a L305P-01 (305W) PS and upgraded the memory to 4Gb. Running XP but switching over Linux, mostly Fedora 18.

The Dual slot card requires some slight changes - remove the bracket as it is not required to hold in the card once it is in the PCI-e slot.

speedstep · Answer

Most Dual Slot cards WILL NOT FIT because they are physically too large.  If you want to use a full size card look at a precision 380 390 xps 400 410 chassis instead.

Locked Topics – Desktops General

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