<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV></DIV><FONT class="Apple-style-span" face="Verdana" size="2" style="font-size: 14px; "><SPAN class="Apple-style-span" style="font-size: 13px; ">Dual PowerPC G4 7447A CPUs running at 1.6 or 1.8 GHz are the only MDD upgrades that I know of.</SPAN></FONT><BR><DIV><FONT class="Apple-style-span" face="Verdana" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Verdana" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;">I upgraded my MDD 1.25 GHZ G4 with the dual 1.8 GHz which, as far as performance is concerned, ran quite well. The big problem with that upgrade is the heat generated by the 7447 chips. It was just too much to bear. I had memory problems with the chips nearest the heat sink. The temperatures reported were quite high - a good 50 - 60 degrees F higher than the single 1.25 GHz Stock Mac CPU. The upgrade's heat sink was too hot to touch. The heat sink on the stock 1.25 MDD is barely warm by comparison. I returned that upgrade because of the temperature problems.</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Verdana" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Verdana" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;">Newer Technology has announced new G4 upgrades using the 7448 CPU which is said to run much cooler. They do not currently have this for the MDD, however. I have e-mailed Newer Technology showing my interest in a 7448 upgrade for the MDD G4 but have not heard from them. You might try contacting them.</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Verdana" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Verdana" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;">Good luck and please post your experience if you upgrade.</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Verdana" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Verdana" size="3"><SPAN class="Apple-style-span" style="font-size: 13px;">Best regards - Bob S </SPAN></FONT></DIV></BODY></HTML>