Dell Optiplex 755 USFF upgrade to E8400?

The 755 uses the intel® Q35 express Chipset

Q6xxx series)

• Intel® Q35 Express Chipset with 82801IDO I/O Controller Hub (ICH9DO)

Spec says so at Intel so With the correct Bios I would say Yes no problem.

Processor Type - Intel® Core™ 2 Quad - 1066MHz FSB, LGA 775, 8MB L2 cache,

Intel® VT, Enhanced Intel SpeedStep® Technology, Intel® 64 and Execute Disable Bit (Q6xxx series)
Intel® Core™ 2 Duo - 1333MHz FSB, LGA 775, 4MB L2 cache, Intel® vPro™ Technology, Intel® VT, Intel® TXT, Enhanced Intel SpeedStep® Technology, Intel® 64 and Execute Disable Bit (E6x50 series)

Intel® Core™ 2 Duo - 800MHz FSB, LGA 775, 2MB L2 cache, Enhanced Intel SpeedStep® Technology, Intel® 64 and Execute Disable Bit (E4000 series)
Intel® Pentium®- 800MHz FSB, LGA 775, 1MB L2 cache, Enhanced Intel SpeedStep® Technology, Intel® 64 and Execute Disable Bit (E2000 series)
Intel® Celeron®- 800MHz FSB, LGA 775, 512MB L2 cache, Intel® 64 and Execute Disable Bit Chipset Intel® Q35 Express Chipset (ICH9DO)

Intel® Q35 Express Chipset with 82801IDO I/O Controller Hub (ICH9DO)

Compatible Processors

Expand All

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  • View the Intel® Core™2 Quad Processor Q8200 (4M Cache, 2.33 GHz, 1333 MHz FS

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

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

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

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

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

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

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

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

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

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

  • View the 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)

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

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

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

• Intel® Pentium® Processor E6800 (2M Cache, 3.33 GHz, 1066 FSB)

  • View the Intel® Pentium® Processor E6800 (2M Cache, 3.33 GHz, 1066 FSB)

• Intel® Pentium® Processor E6600 (2M Cache, 3.06 GHz, 1066 FSB)

  • View the Intel® Pentium® Processor E6600 (2M Cache, 3.06 GHz, 1066 FSB)

• Intel® Pentium® Processor E6700 (2M Cache, 3.20 GHz, 1066 FSB)

  • View the Intel® Pentium® Processor E6700 (2M Cache, 3.20 GHz, 1066 FSB)

• Intel® Pentium® Processor E6300 (2M Cache, 2.80 GHz, 1066 MHz FSB)

  • View the Intel® Pentium® Processor E6300 (2M Cache, 2.80 GHz, 1066 MHz FSB)

• Intel® Pentium® Processor E6500 (2M Cache, 2.93 GHz, 1066 FSB)

  • View the Intel® Pentium® Processor E6500 (2M Cache, 2.93 GHz, 1066 FSB)

• Intel® Pentium® Processor E2140 (1M Cache, 1.60 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E2140 (1M Cache, 1.60 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E2180 (1M Cache, 2.00 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E2180 (1M Cache, 2.00 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E2200 (1M Cache, 2.20 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E2200 (1M Cache, 2.20 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E2220 (1M Cache, 2.40 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E2220 (1M Cache, 2.40 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E5200 (2M Cache, 2.50 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E5200 (2M Cache, 2.50 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E5400 (2M Cache, 2.70 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E5400 (2M Cache, 2.70 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E5500 (2M Cache, 2.80 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E5500 (2M Cache, 2.80 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E5700 (2M Cache, 3.00 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E5700 (2M Cache, 3.00 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E5800 (2M Cache, 3.20 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E5800 (2M Cache, 3.20 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E5300 (2M Cache, 2.60 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E5300 (2M Cache, 2.60 GHz, 800 MHz FSB)

• Intel® Pentium® Processor E2160 (1M Cache, 1.80 GHz, 800 MHz FSB)

  • View the Intel® Pentium® Processor E2160 (1M Cache, 1.80 GHz, 800 MHz FSB)

• Intel® Celeron® Processor 450 (512K Cache, 2.20 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor 450 (512K Cache, 2.20 GHz, 800 MHz FSB)

• Intel® Celeron® Processor E1600 (512K Cache, 2.40 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor E1600 (512K Cache, 2.40 GHz, 800 MHz FSB

• Intel® Celeron® Processor E3500 (1M Cache, 2.70 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor E3500 (1M Cache, 2.70 GHz, 800 MHz FSB)

• Intel® Celeron® Processor E1200 (512K Cache, 1.60 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor E1200 (512K Cache, 1.60 GHz, 800 MHz FSB)

  • Intel® Q35 Express Chipset with 82801IDO I/O Controller Hub (ICH9DO)

• Intel® Celeron® Processor E1400 (512K Cache, 2.00 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor E1400 (512K Cache, 2.00 GHz, 800 MHz FSB)

• Intel® Celeron® Processor E3200 (1M Cache, 2.40 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor E3200 (1M Cache, 2.40 GHz, 800 MHz FSB)

• Intel® Celeron® Processor E3300 (1M Cache, 2.50 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor E3300 (1M Cache, 2.50 GHz, 800 MHz FSB)

  • Intel® Q35 Express Chipset with 82801IDO I/O Controller Hub (ICH9DO)

• Intel® Celeron® Processor E3400 (1M Cache, 2.60 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor E3400 (1M Cache, 2.60 GHz, 800 MHz FSB)

  • Intel® Q35 Express Chipset with 82801IDO I/O Controller Hub (ICH9DO)

• Intel® Celeron® Processor 440 (512K Cache, 2.00 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor 440 (512K Cache, 2.00 GHz, 800 MHz FSB)

• Intel® Celeron® Processor E1500 (512K Cache, 2.20 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor E1500 (512K Cache, 2.20 GHz, 800 MHz FSB)

• Intel® Celeron® Processor 430 (512K Cache, 1.80 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor 430 (512K Cache, 1.80 GHz, 800 MHz FSB)

• Intel® Celeron® Processor 420 (512K Cache, 1.60 GHz, 800 MHz FSB)

  • View the Intel® Celeron® Processor 420 (512K Cache, 1.60 GHz, 800 MHz FSB)

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

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

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

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

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

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

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

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

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

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

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

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

  • Intel® Q35 Express Chipset with 82801IDO I/O Controller Hub (ICH9DO)

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

  • View the 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)

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

  • Intel® Q35 Express Chipset with 82801IDO I/O Controller Hub (ICH9DO)

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

  • View the 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)

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

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

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

• Intel® Core™2 Duo Processor E8190 (6M Cache, 2.66 GHz, 1333 MHz FSB)

  • View the Intel® Core™2 Duo Processor E8190 (6M Cache, 2.66 GHz, 1333 MHz FSB)

• Intel® Core™2 Duo Processor E8200 (6M Cache, 2.66 GHz, 1333 MHz FSB)

  • View the Intel® Core™2 Duo Processor E8200 (6M Cache, 2.66 GHz, 1333 MHz FSB)

• Intel® Core™2 Duo Processor E8300 (6M Cache, 2.83 GHz, 1333 MHz FSB)

  • View the Intel® Core™2 Duo Processor E8300 (6M Cache, 2.83 GHz, 1333 MHz FSB)

• Intel® Core™2 Quad Processor Q9400S (6M Cache, 2.66 GHz, 1333 MHz FSB)

  • View the Intel® Core™2 Quad Processor Q9400S (6M Cache, 2.66 GHz, 1333 MHz FSB)

• Intel® Pentium® Processor E6500K (2M Cache, 2.93 GHz, 1066 MHz FSB)

  • View the Intel® Pentium® Processor E6500K (2M Cache, 2.93 GHz, 1066 MHz FSB)

• Intel® Core™2 Quad Processor Q9450 (12M Cache, 2.66 GHz, 1333 MHz FSB)

  • View the Intel® Core™2 Quad Processor Q9450 (12M Cache, 2.66 GHz, 1333 MHz FSB)

• Intel® Core™2 Quad Processor Q6600 (8M Cache, 2.40 GHz, 1066 MHz FSB)

  • View the Intel® Core™2 Quad Processor Q6600 (8M Cache, 2.40 GHz, 1066 MHz FSB)

• Intel® Core™2 Quad Processor Q6700 (8M Cache, 2.66 GHz, 1066 MHz FSB)

Many many thanks 'flash for the quick responses today and your help. FYI the unit is currently running a Xeon3070 with no issues and it isn't on the official Dell compatibility list either--but since it is a twin to the E6700 I didn't have as much hesitation with that swap as I did jumping from 65nm Conroe down to 45nm Wolfdale.

Also thanks Speedstep for the elaboration on the Q35 chipset, I knew it would support the cpu but as is known sometimes OEM vendors modify their bioses so I asked to see if anyone knew firsthand if Dell had "dampened" the compatibility for system stability reasons in the USFF version.

Just to be clear, the power supply for the USFF is 220 W according to the tech specs chart, not 150W.  

I am running the latest BIOS which is A22, so that should not be a problem at all.  

Also, the E8400 is essentially the same thing as the E6850, just with the 45 nm process instead of the 65 nm.  So the power consumption should be the same, and the power should not be an issue.  The real issue in question is whether or not Dell  has added support for the 45 nm Core 2 Duos in their BIOS, because they are supported natively on the chipset by Intel.

I am just wondering if you ever tried this processor and if so, what were your findings on your USFF machine?

The power supply for the  USFF is 150W not 270W so for many processors I would say the answer is not clear.

NOT UPDATING BIOS TO A21 could be a real issue.

130W processors Are not going to work in a USFF with 150W power supply,

E8400

E6850 is ok.

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

The QX8200 May not work due to

CPUID   010677h

Core stepping   M1

I also think the 130W and 150W cpu's would require a Tower with Greater than

305W power supply AND the Copper heatpipe heatsink.

These are the Quads we validated -

N652J 3.00GHz YorkfieldQuad Core Q9650, 12MB Q9650

F886J 2.83GHz Yorkfield Quad Core Q9550 12MB, 1333FSB, E0

N650J 2.66GHz Yorkfield Quad Core Q9400, 6MB, 1333FSB, R0

MP627 2.66GHz Kentsfield Quad Core Q6700, 8MB, 1066FSB, G0

Dell recommends applying this update during your next scheduled update cycle. The update contains feature enhancements or changes that will help keep your system software current and compatible with other system modules (firmware, BIOS, drivers and software).

UPDATING the bios must be done BEFORE trying another cpu.

O755-A21.exe

SLB5M

SLG9S

V core  0.85V - 1.3625V

CPUs, related to Intel Core 2 Quad Q8200  

CPUs, related to Intel Core 2 Extreme QX9650  

"Just to be clear, the power supply for the USFF is 220 W according to the tech specs chart, not 150W"

The external Brick is not the same as the power rating for the INTERNAL MOTHERBOARD VRM's

This is also why the Quads are Not listed as compatable with the USFF.

This is not to say that it wont work. I dont know fer shuure cuz I aint got one.

HOWEVER this is also not a Guarantee that it DOES work.

Without Updating the Bios to A21 it is highly LIKELY that it will not post OR it will simply state unsupported processor and either HALT or make you Press F1 to continue Each and every time.

??? I didn't make this up. When I go to support and look for downloads, it filters results based on my service tag. That gives me filtered results based on my particular service tag (USFF) and this is copypasta from that resultant page.

"Dell OptiPlex 755 System BIOS

OptiPlex 755 System BIOS

Release Date: 6/30/2011

Importance: Recommended

Version: A19 See Previous Versions

The following formats are available for the file you have selected

File Format: Windows/DOS Get Driver Download File

Add To My Download List Add to My Download List

File Name:

O755-A19.exe

Description: This file format consists of a BIOS executable file. The Universal (Windows/MS DOS) format can be used to install from Windows XP, Windows 2000, NT, Windows 9X, Windows ME or a MS DOS environment.

Download Type: HTTP

File Size: 2MB"

Now, if it is true and supported that any 755 bios will work on any flavor 755 from desktop >>> USSF, I will go ahead and reflash to the latest supported compatible bios. Who knows, that may fix my USB issues as well... let me know!

Not sure why you made up that.  

There is only 1 BIOS for ALL Models not a separate Bios for USFF.

BIOS - BIOS

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

A22 is Very New

Also, would there be a model difference in which I should choose between the models of:

SLAPL (C0)

SLB9J (E0)

I think I am just going to bite the bullet and order the E8400.  If it doesn't work, I can just simply send it back and then get the E6850.  And I am indeed using the A22 on the USFF, its the newest.