dell inspiron 1720 random turn off

[p.larner]

i have a 1720 running win7 64bit and a t9500 cpu+ 4gb ram,it has started shutting down at random,i assumed it was overheating due to the cpu upgrade,i cleaned the heatsink+ replaced the thermal paste,it made no change,i notice tho if i remove the battery its fine,its a chineese replacement battery about 6 months old,is this a common issue,is there a fix?.

[tunk]

If the new CPU draws more power than the old, then the PSU could be marginal.

[p.larner]

did i say it is ok on mains with the battery removed,it only does it on mains power with the battery in the lappy.