While reducing your voltage and disabling HT reduces the temp of your CPU, it also reduces the processing power of your system. What your might want to do instead is just reduce how much BOINC is running on your system. That way you still have some extra horse power available whenever you feel like doing anything CPU intensive.
To reduce the BOINC load, you can reduce the number of cores that are allowed to run or reduce the % of CPU on time.

Note, HT on vs off is about a 33% difference in performance for most projects (throughput not necessarily pts)

Exactly same experience with an i7-920 here
Furthermore I operate - as far as this machine is available - an i7-860 overclocked @ 3,8 GHz (yes, three point eight) with HT on and no errors or any other sign of degradation. Of course, there is a state-of-the-art cooler in place. Please do not try this with the boxed cooler.

Hello fabiopb,
The benchmark is a single thread. Don't use it to determine overall throughput of multiple threads in a hyperthreading environment. People report a 25% increase in throughput for WCG using i7 hyperthreading.

Personally I start making frowny faces while the CPU temps are still in the 50s (C) but realistically temps in the 60s are OK.

Lawrence

Hi Fabio,
for sure there are many indicators that with HT on you will get more performance from the machine.

I can confirm that using HT on you can crunch about 25% more tasks than without HT on for this specific i7 processors family (except for extreme ones processors...), if you will crunch at stock clocks.

Additionally the energy consumption of processor will be a little bit small using HT off. It will involve more factors to determine with precision, like what is the kind and brand of your motherboard, kind and brand of your RAM, kind and brand of your hard disks, kind and brand of your VGA (if there is one or more in the machine), kind and brand and eficiency level of your power supply, kind and brand of your cooler setup, and so on...

For sure it will depend on what the project mix you will setup to run in the machine, and till the operating system that you will install (W 7 32 or 64 Bits, Mac, Linux, etc...).

So, the combined factors to determine the result of performance to have sure about be better or not in your specific case, is so complex and depend on your own effort to discover it during some tunning time over your machine, until get a satisfactory result/bench that will be smooth under your perspective.

And to reduce the temperature, the better way I guess will have an excellent colling system in your machine, despite of you turn off HT you will have some relevant reduction in processor temperatures (and in machine overall too) if you can use a high performance level cooling/chilling system.

There are some posts across the forums where people talk about this comparisons in i7 processors, I don't remember more who post it, but a deep search could be found anything about it.

Edit: some adds in wording, and just to suggest that if you would like to discuss a little bit more about it and change more information, I will be available to chat you in Portuguese via MSN. Pick my address at the correspondent signature profile icon below. Have a nice day.

When I look at your numbers your CPU is clearly not overclocked and you run stock frequency 3.06 Ghz. If you haved one of those very crammed mini tower from Dell, HP etc. then you have to look by yourself what is possible to do out of my advices here under:
Switching off the HT is not an issue. Temperatures of 90 Degrees are abnormal, and you are having a cooling problem not a CPU load issue.
Check core temperatures when running idle. What temperature do you have. If your cooling is efficient you should be around 28 and even lower if you are with external air room temps of 18-20 deg C.
Check that your CPU heatsink is very firmly attached with good and even pressure. Check that the fan does run with at least 2000 rpm speed, and check that the blades and that the coolers fins are clean and without dust. Otherwise use compressed air to clean. Dust can cook your machine. If it is not well attached then dismount it, clean the two contact surfaces well (acetone is excellent for that) and then put some good thermal paste like Arctic Silver 5 or even better a ceramic based one, and the remount it.
Better of all like mentioned by Bearcat, if you have a standard cooler change it with a good one and use a good thermal paste. The size and number of fans you can attach will depend on the available space you have.
Good Luck