I currently have DDR3200 memory in my system but the FSB is 333 Mhz (with a 266Mhz FSB Athlon). Will I gain or loose any preformance by running the memory at 400Mhz and the FSB at 333Mhz. Can setting it up like this cause any instability?
It's usually best to run ram and fsb at the same speed. I very much doubt you will see a performance increase running the ram faster than the fsb. You'd be better off running it at 333mhz ddr and trying for tighter timings
If your fsb:dram ratio remains the same then chances are you wont be able to set the ram to 400mhz, as your cpu wont cope with the speed you would be increasing that to as a result. Best thing to do is set your fsb to 200 and multiplier to 10 or whatever, so that they sync and then you can crank the ram up as well.
I take it your default is 12.5x166=2.08ghz (XP2600+). A safe way to test is to set 10x166 and see if you get 1.66ghz as expected or are still stuck at 2.08ghz. Just sticking in 10x200 is not a good idea at all, if 10x can't be set you'd be using 12.5x200=2.5ghz (even XP3200+ only runs at 2.20ghz with 11x200 and 512k L2). On top of all that your mobo may not even be capable of 200/400FSB. Anyway as said 99% of the time best perf is achieved by running the FSB and RAM in sync. Running slower is where the big perf hit comes in, running faster can simply mean the extra RAM speed can't be utilised and perf hit is then possible as they don't match up each cycle. The biggest exceptions to this are when using some IGP (integrated gfx, eg nForce) and the KT333 chipset which gained a few percent by using DDR333-PC2700 at 133/266FSB. As such it is possible that the others like the KT400 can gain perf by using DDR400-PC3200 at 166/333FSB. Even so as mentioned you can often gain a few percent simply by using tighter RAM timings which is easier at lower speeds, if your RAM is capable of tighter timings of course. So long as your mobo supports async RAM speeds and your RAM is rated for the speed at which you run it there should be no stability issues nor risk at all. So basically a lot depends on other factors, primarilly what your mobo is (esp its chipset).
It's an nforce2 chipset and is capable of 400Mhz FSB. Thanks for your help i'll do some testing over the weekend.
