Memory Question

[YabbyU]

I am thinking of getting kingston hyper x DDR500 memory for my new upgrade (circuit city gift card )
will that run on a mother board that says it only supports DDR400? Would I need to underclock the memory? And would that be a stupid thing to do.

Im upgrading to a MSI neo2 platinum and an AMD 3500 939.
thanks

 

[Peter]

Most forgotten fact here: The mainboard supplies the clock frequency to the RAM, and the RAM has to sync up to that (hence the name, synchronous DRAM). Thus, the RAM must be specified for AT LEAST the mainboard provided frequency. If it could go even faster, fine, but it'll make little difference - maybe you can choose a tad more aggressive timings, but if your mainboard can do no more than 200 MHz and your RAM could do 250, it'll still be run at 200.

 

[YabbyU]

Thank you Peter, that helps me out alot.

 

[imported_Aelius]

The only time you need RAM above PC3200 (DDR400) is if you are overclocking and need the added RAM speed to run 1:1 with your overclocked CPU.

There's absolutely no other reason to buy fast RAM like that.

If you don't overclock then just get PC3200 RAM and run it at tight timings.

Take me for example.

I'm building a system by the end of next week that is similar to yours. A64 3500, MSI K8N Neo2 etc...

The RAM I'm getting is PC4000. Now most RAM at this high speed will have piss poor timings which, despite popular belief, is a major factor or A64 performance. You can search for benchmarks which show that timings are actually more important than FSB.

Keep in mind the A64 is not FSB starved like the Intel. It doesn't need a massive FSB to boost performance, and so memory timings play a much larger role in deciding performance.

Having said that you probably wouldn't want to run your CPU out of sync with your RAM. It does funny stuff, not to mention drop performance, and so you are forced to run your system at a specific speed.

You probably seen forums where people are talking about only reaching 234FSB or 216FSB with their heavily overclocked system.

That's cause they are running very tight timings using PC3200 RAM that generally cannot run tight timings at fast RAM speeds like DDR500.

There are some exceptions. Certain brands of RAM from certain companies can run tight timings even at high RAM speeds.

The best known brand for A64 is the OCZ Enhanced Bandwidth. It's performance and compatibility has been by far the best of any RAM on the market for A64. This is partly due to the type of RAM chips used, which happen to come from Micron. Micron has had great success on A64.

Another one that just poped up is OCZ PC3700 Gold Rev3 and OCZ EL PC4000 Gold Rev2. They are using a new Hynix chip which for some reason also works really well on A64 systems. That was surprising since so far Hynix chips have had very poor performance on A64.

Personally I'm going to use the OCZ EL PC4000 Gold Rev2 because I want to get as high FSB I can reach without loosing timings. I also don't like that with most RAM you have to pump a lot of voltage into the RAM to get most of the performance from it. With the RAM I'm getting that's not the case. It runs great at 2.6v.