Is that 53c Under load? or just idle, If that is Idle temp the swing from 42c to 53c seems to high. Seriously get some artic silver clean the cpu really good with rubbing alcohol.
put a tiny dab on artic silver on the cpu and spread it with a credit card, DO NOT USE your fingers, fingers are oily and oil=bad. At idle I don't think you should have more than a 3-4c temp difference from the mobo.
I use a ZalmanCU cooler and my CPU is actually 3c lower than my Mobo temp at idle and never more than 9c under load.
42c seems high for mobo temp, what is the temp in the house or room the comp is in?.
2.4c @ 3.0
4 Maxtor 250gig serial ata drives
Viewsonic 17" tft
ATI 9800Pro @ stock