I have upgraded one of my old computers from 512MB RAM to 1GB by buying another PC3200 DDR400 512MB module. Upon booting Windows XP after the installation of RAM, BSODs with various errors show up (sometimes before loading to the desktop, sometimes after the desktop has loaded). Some of the errors include: IRQL LESS THAN EQUAL error, and another error that has the word 'Page' in it (I forgot if it is Page fault or Page file). I have traced this down to the BIOS Memory settings. Before the upgrade, I have set other settings to the optimal setting that the BIOS can allow me, by reading this guide: http://www.techarp.com/freebog.aspx , without any problems. Upon upgrading, setting the DRAM Command Rate to 2T will prevent the BSODs (before the installation of the new module, this setting was set to 1T and my system worked fine without any BSODs). I am wondering if there is another way I can get my system to work while still setting the DRAM Command Rate to 1T. As I have seen from various websites like this one: (Techwarelabs.com) http://www.techwarelabs.com/reviews/memory/memory_timings/index_3.shtml , there is a performance increase if the DRAM Command Rate is set to 1T. I also would like to know if the performance gain is not that significant and if it is better if I just leave it at 2T? I am also wondering if module order matters (based from closeness to the processor) in performance and stability. I have found out thru Everest Home Edition that the new module I bought has a slightly slower memory timing that my old one (I have set my old module closer to the processor). This system is Windows XP, P4 2.4 GHZ. ASUS P4VP-MX motherboard, my BIOS is also recently updated . My motherboard contains two RAM module slots, each slot has a PC3200 DDR4001 512MB RAM - 1GB total.