does the default raid opotion add more heat to the mobo?

I have 2 similar e7240.

Mine e7240 i5 4300 16gb 2 dimms undervolted -70mv, turbo turned off, 1080p dell 1601 wigig, raid on in the bios
Gf e7240 i5 4300 8gb 2 dimms not undervolted, turbo turned off, 1366 x768, dell/intel 7260ac, ahci on in the bios

I'm running significantly hotter by 5-8 degress celcius during idle. So either the 1601 wigig is much hotter or the raid bios option appears to be the culprit.. I've actually redone the thermal paste on both. It appears dell puts paste on the cpu die but forgot paste on the igpu die. Seen this on a e7440 also.

 

If you are running Dell's Windows installation then you should be able to turn of RAID in the BIOS without any problems because the drivers for the different modes are pre-installed. However, I don't think that's the cause because I haven't seen any significant different in power consumption between using RAID and AHCI.

I would compare at the CPU activity and power consumption. Task Manager will show the % CPU usage. You can use Perfmon to check whether both computers have the same C state usage and Battery Info View to see the power drain when running on battery. HWiNFO > Sensors reports CPU package power.

If you find that both notebooks, under the same operating conditions, have similar CPU behaviour but different power drains then you might have just got two similarly badged CPUs that lie at opposite ends of the acceptable power consumption within the overall specification for the bin. If your CPU is running hotter and using more power then it's likely to have a lower sustained maximum speed. you can check this out by running wPrime 1024 while watching the CPU speed using HWiNFO.

John