DDR2 Memory Ram differences?
 

So I bought the Core2Duo 2.33ghz win7 Dell Optiplex 755. Now its running 32bit and came with 2gb ram. I would like to upgrade to 4gb ram to maximize the 32bit performance. Stock it came with 5300 DDR2 but I see that I can get 8500 DDR2. Will that make a big difference or should I just get 2 more 5300 DDR2 sticks? If I go 8500 then I would have to get 4 sticks.

If your PC is not rated for 8500 it will only address what it can.

If the PC was designed for nothing faster than 6400 and you put in 8500 you'll get 6400.

Check your specs.

Thanks. How do I check the specs? I can probably find a Dell Optiplex 755 Small Form Factor manual online or would this be something I look up on the physical unit itself? Sorry for the noob questions.

I found this manual and I know that I have a 2.33ghz VT (and there is only one of those on there) but I have no idea what I am looking for to figure out if I should buy more 5300 or go higher and get 4gb of it.

http://www.dell.com/downloads/global/products/optix/en/opti_755_techspecs.pdf

pg 12 of your PDF lists max chip as PC2-6400 so I'd stick with that.

Ok thanks. Is it worth buying 4gb of 6400 if I have 2gb of 5300 and can just get 2 more? Is the difference big?

Not a whole lot, you'll have other choke points than cpu->ram communication speeds....

With the price of RAM I would replace the 5300 as your timings and CAS latency will most likely not be the same. It may not cause any issues but it can. For the $25 I wouldn't chance it.

4G is way better then 2
I did notice when I jumped from 2 to 4G
5300 vs 6400 not at all noticeable
maybe a few points on a test score

just buy the cheapest 2 1G sticks 53 or 64 or what ever as long as it is ddr2 NO#3

Run the scan at Crucial.com as referenced.

Remember that the 4GB memory limit for a 32 bit OS is a hardware limit - based on the # of address lines on the CPU.

What does that mean? Well, basically it means that ANYTHING else in the machine that needs to map into that address space (like the BIOS, I/O space, video RAM) all has to come out of that 4GB total - and it will.

The OS can only "see" 4GB total - so a 512MB video card will knock that down to 3.5GB available to the OS immediately.

Most DDR memory is backwards compatible with slower spec memory of the same type. Much of the slower spec memory will actually run at the faster speeds. Most reputable suppliers will allow returns/exchanges.

Best practise is usually to get 4 sticks of identical memory if you can; likely won't matter for that machine - but some machines won't enable dual/quad memory buffering unless you populate the banks with identical memory.

I'd suggest you check and see what your actual memory usage is for a typical workload; if you're only using 1GB of RAM, then buying 4GB won't get you any actual speed, although it'll help the OS buffer the hard disk - but buying an SSD with the same money would be 10x faster.

Before spending any money, ensure you clean/compact the registry with CCleaner and run a decent defragger (like Defraggler, from the same folks, much better than the toy one that comes with XP) on the disk. I tell my mum to do this about every two weeks. You might be shocked how much difference this makes (and how many dumb programs open the registry 3-4 times a second looking for keys that don't exist - any inefficiency there can really hurt performance).

If you don't have any expensive, proprietary software on the machine - like all you do is web browse etc. - you can avoid all this by just blowing away XP and putting an efficient OS and a decent browser on the machine. It'll fly in comparison.