CanadaRAM is right, why monitor the temps looking for a problem when returning it and getting the right RAM will make sure there shouldn't be a problem and no need to monitor the temps
Well, I can sure comment on that; right after I purchased my 2007 Mac Pro, I ordered more RAM from OWC. And then, instead of operating temps of 130-140F, I was seeing temps of 250-260(!), for just the OWC RAM. Physically, they looked the same as the Apple RAM. By the time I'd installed the temp. widget, iStat Pro, the video card, an ATI 1900, was beginning to fail (pixelation, freezes) during gameplay. It was physically located right above the over-heated RAM, & didn't dig it. I ended up replacing the video card (with a newer revision 1900 card) and the OWC RAM. All problems solved. OWC got the same high temp readings as I on the returned RAM, & didn't have a clue as to the immediate cause. Their RAM replacements to me ran at over 100 degrees cooler. Conclusion: Monitor your temps!