I replaced old graphic card (9600GT) with new(GTX260extreme+) and noticed motherboard temperatures are 10 to 15`C higher They used to be around 38`C now they are 48 to 54`C when playing games. I did not overclock anything,everything is on default values.
CPU Q6600@2,4 GHz PSU Chiftek 550W MEM Kingston 4 Gb @800 MHz GPU Leadtek GTX260 extreme+ MOBO Gigabyte EP35-DS3R
More aboutidle temperature
with a GTX260extreme+ i think it's just fine if the temps around 50'C when playing games .... It plays well, isn't it? If it fine then don't worry about it.
Idle = Idle, so if you're playing a game that counts as stressed not as idle.
And what did you expect? The card you have now uses about twice the power, or even more, than a 9600GT. So temperatures will be higher yes.