Sigh, Memclock index value is the maximum speed of your memory, which is where your memory divider is. Look for something that would allow you to go anywheres from 200-400 in 1mhz jumps...... That is what you would want to raise, and with the LTD it would be safe at 4x till you hit 251 which you would need to drop it to 3x AND RAISE IT VERY SLOWLY, like 3-5mhz at a time and running prime for 10-30 min, if stable go up some, If you fail raise the Vcore very slightly and try, if you fail then i dunno ask nubius, he is the god......
Also leave the timing at 2T unless you can easily get it stable with 1T timings which MAY require more voltage to the RAM and some ram hates more voltage.....