Re the 630…May have a dead PSU. 
Will investigate wether it's repairable, if not, will part out.
Re the 6100… Not booting reliably, possibly a dead PRAM Battery, and when I do get it to boot, it seems to have very little RAM, and if booted from the internal drive I get a 'Bus Error'. When the RAM is removed, I get a Sad Mac Error 0000000F 00000069, can't find any info on this, please advise. it's a shame if this doesn't work, it's badged as an AV model.
Re the 7220…works fine, except the thing gets too warm, on investigation it was a cactus PSU fan. Is this worth fixing?
TIA
Nick
Will investigate wether it's repairable, if not, will part out.
Re the 6100… Not booting reliably, possibly a dead PRAM Battery, and when I do get it to boot, it seems to have very little RAM, and if booted from the internal drive I get a 'Bus Error'. When the RAM is removed, I get a Sad Mac Error 0000000F 00000069, can't find any info on this, please advise. it's a shame if this doesn't work, it's badged as an AV model.
Re the 7220…works fine, except the thing gets too warm, on investigation it was a cactus PSU fan. Is this worth fixing?
TIA
Nick