It is possible to make a heatpipe-cooler for the 770 (and probably the 600) series to improve cooling for modded Pentium III machines. On the 770X/Z, the HDD-Slot must be used because there is no other space available. Of course, a standard 2,5" HDD will not fit anymore after the mod, so a CF-Card or a 1,8" HDD (e. g. from Toshiba) and a selfmade adapter is required (maybe for CF-cards, a standard 2,5" to CF-card-slot adapter from Ebay could fit). After the mod, the temperatures (Pentium III @ 850mhz / 918mhz) never went above 70° C while executing prime95 in-large-FTT test. Before the mod, i was not even able to use Windows XP for more than half an hour because the temperature went up to 90°C and above in idle (I powered off at this point).
The cooler is made out of some 2mm and 1 mm copper plates, a radial fan from a compaq n610c heatsink (any other 45mm to max 50 mm radial fan should work), a copper radiator from another notebook heatsink and heatpipes from an Arctic Cooling Accelero X1 VGA heatsink. This is a third-party cooler made for nvidia Geforce 6800 and 7800 VGA series (Accelero X2 for ATI cards also works). The reason why I used the heatpipes from this cooler is that they are flat and therefore easy to solder on the copper plates.
Here are some photos (800x600, ~50kB each):
In this review there are some photos of the Accelero X1:
http://www.hardwaresecrets.com/article/346/1
For the 600 series it should also be possible to make such a cooler. But you will have to remove the modem card to get some space available. The heatpipes are ~ 15 cm long, ~5mm wide and 3mm thick.
The first step to isolate the heatpipes is to remove the plastic cover as shown in the link above. Then you can pull of the soldered aluminium fins with flat pliers or something similar. After that you can either already try to remove the heatpipes with a gas burner or cut the copper and aluminium plates into pieces so you do not have to heat everything up so long. Be careful not to overheat the heatpipes or to damage them with the saw. If the are opened once, they are useless.
Maybe there is also an easier way for the 600 series. In this thread the user ChrisL used a heatsink from a compaq n610c and it seems that it fits the 600 series with some small modifications. See the last post: http://www.wimsbios.com/phpBB2/topic4046-615.html
For overclocking the 850mhz processor to 1Ghz, there is the possibility to use a turbo-PLL which enables you to overclock FSB, PCI and AGP without also overclocking USB, floppy and REF-outputs used for clock, etc. Unfortunately at targed FSB of 120Mhz the PCI is already 40 Mhz(standard 33Mhz) and AGP at 80Mhz (standard 66Mhz) which could cause stability problems. See this link:http://www.overclockers.com/tips745/
Another method could be to replace the cpu on a 750Mhz, 800Mhz or 850Mhz module with a µPGA2-Socket fom a dead T20, T21 or T22 system board and to use a 1Ghz µPGA2-CPU. Electrically and mechanically, they are compatible. All MMC2-CPUs up to 700Mhz use smaller capacitors , so I would not recommend to use them for the mod. See my posts in this thread: http://forum.thinkpads.com/viewtopic.php?t=53785
I apologise for any faults in this post.
greetings from el-sahef




