performance - Using two DDR-2 800 MHz instead of two DDR-2 533 MHz RAM

My PC has following hardware right now:

• Intel Core 2 Duo E6600 2.4 MHz


• ASUS P5B-VM Motherboard


• 1 GB DDR 2 533 MHz RAM


• 2 GB DDR 2 800 MHz RAM


• 7200 RPM SATA 2 HDD


• NVIDIA GeForce GTS 250 1 GB

My motherboard supports maximum of DDR 2 800 MHz RAM. Since one of my RAM is rated 533 MHz, the motherboard adjusted both RAM speed to 533. (I bought 2 GB RAM 2 years after I bought the whole system.)

I use Windows 7 Ultimate. The system rating index for my PC is 5.5, which is the slowest one among all parameters. This 5.5 rating comes from RAM speed.

I want to know, if I replace the 533 RAM with 800 RAM, will the overall performance increase be noticeable? For your information, my PC is used for gaming, graphics design (AutoCAD, Sketchup, Corel Draw etc), video editing (Corel VideoStudio Pro X3) and conversion (VideoStudio & Handbrake), and other general purpose (internet, listnening music, watching movies etc.).

It is not possible for me to benchmark the upgrade until I buy the RAM. So I'd like to know in advance if the upgrade will be noticeable and then I can buy it.

Thanks in advance.

Answer

Your machine will be running all your RAM at the speed of the slowest (the 533). Whether there will be much difference running at 800 depends on what latencies the RAM and memory controller support between them and which benchmark you run, but it is highly unlikely to be slower.

If you take the slower DIMM out and run with just the 2Gb@800 the motherboard should run at that speed - you can then rerun any benchmarks and check some of your usual software tasks (though not tasks that would usually need the extra RAM).

I suspect that you will see very little real world difference unless you are number-crunching over large in-memory data sets. Most of your tasks will be more I/O bound than CPU/RAM bound, just plain CPU bound (if your CPU has gobs of cache), or (in the case of games) far more sensitive to graphics card performance (and the performance of the bus the graphics card is connected through). Of the tasks you list in your question, I think video conversion is most likely to be were you'll notice a difference, but even that is probably be more I/O bound (when reading large files to process) and CPU bound (doing the hard work on each frame in tight loops over cached data) so I think the difference will be small.

If you do notice a boost from the RAM running faster, then upgrade the 1Gb DIMM to a faster model to get your full 3Gb back (or get 2Gb if you are running a 64-bit OS that can use it all - you'll probably find the price difference between 1Gb and 2Gb very small at the moment) - if not just put the current 1Gb DIMM back in.