Optiplex 755 USFF cpu and ram upgrade

Ram Speed depends on CPU FSB.

755's do not support DDR3.

1066mhz fsb cpus require PC2 8500 Ram.

800MhZ fsb cpus require PC2 6400 Ram.

And afaikt thats the max speed of Ram on the 755 chipset.

ark.intel.com/.../Intel-Core2-Duo-Processor-E6850-4M-Cache-3_00-GHz-1333-MHz-FSB

www.crucial.com/.../mpartspecs.aspx

Memory Type: DDR2 PC2-8500, DDR2 PC2-6400, DDR2 PC2-5300, DDR2 (non-ECC)

Maximum Memory: 8GB

Slots: 4 on tower 2 on USFF

Although the memory can be installed one module at a time, the best performance comes from using matched pairs of modules.

How much memory your Windows OS will recognize depends on which version of Windows you are running. 32-bit versions of Windows will see (and utilize) only 3GB or 3.5GB. To utilize more memory, install a 64-bit version of your OS.

Hi Damo123,

That CPU is supported, and the stock heat sink should be fine.

You do not need different memory. Two 2-GB PC2-5300 modules are $72 on Crucial.

Osprey,

thanks for the advise can you see any problems of using that ram with the e6850 cpu? With Speedsteps advise i am now confused lol.

G.SKILL PC8500 DDR2 2x2gb kit, $65 with free shipping.

I've had nothing but good luck using G.SKILL in my older Dells.

correct me if im wrong as you can tell my knowledge on this is quite bad.

With the e6850 cpu whitch is 1333 fsb, would the ddr2- pc2 8500 be the best match up to it?

Thanks

PC2 8500 is the fastest DDR2 Ram available. Works in ALL 755 models.  With 1333FSB Likely the ram will clock down to 800MHZ aka PC2 6400.  This is just a guess though I am not Dell engineering and I don't have a Cpu to test.

The CPU-Z program would tell you how fast it is or isn't running.  They don't use DDR3 so 1333Mhz ram isn't happening ever.  PC2 5300 RAM does not work with 800MHZ FSB or higher CPUS.

Speedstep,

if the pc2-8500 ram would clock down to 800MHZ i know this was a guess, but if it does clock down i might aswell go for pc2-6400 which is already 800MHZ??

YMMV.  I know that PC2 8500 works with all models all cpus aka it can work at the slower speeds.   I cannot answer that question because I do not have a 1333mhz cpu and do not know what the chipset does with the ram.  I do know that DDR 2 has a max speed of PC2 8500.  Only the designer of the board or perhaps Intel would be able to tell you. My Guess is that 800MHz memory although faster than 667MHz memory will only run at 666.5MHz speed on a 1333MHz FSB. If you guess wrong the ram will not run.:emotion-9:

After looking at dells technical guide it looks to me that you can only put ddr2-667 or ddr2-800, I think it's a q35 chipset?? And on Intels spec says the same about the memory and also says about the supported fsb is 1333MHZ/1066MHZ/800MHZ.

Quads are not happy with PC2 6400 ram and have low frequency Beeeeeep Beeeeep Beeeeep Ram Ram Taste Bad.:emotion-3:

I'm not going to be using a quad processor, it's the c2d e6850.

Will it still taste bad lol

I only say if I have one to test.  Unfortunately I don't.  For any ram must say INTEL compatible Low density or it won't work regardless of speed.:emotion-5: For that cpu I would not try anything less than PC2 6400. Download and install CPU-Z and run before and after so we will know. Then post the picture like I did.

Ok I will give it a go with the pc2-6400 run the CPU-Z should have the CPU tomorrow just need the to get some ram.

After installing everything do i need to do anything on the computer ie bios settings or anything?

Thanks

Nope first thing i did with the computer was update the bios to A22 was on A11 . Also was getting battery voltage low on start up so swapped out the battery today and now thats all sorted . Just ordered my ram and a new hard drive for it so hopefully will have them in a few days then i will fit my new cpu and all that and hope for the best lol