My 1055T at 4.0GHz (286x14) is stable at 1.456volts.
Voltage is ok if the temp is within 60c. However I've experienced that higher voltage makes the CPU inefficient while lower voltage gives more performance at a certain frequency.
For example I get 72 GFLOPS with1.53volts at 4.0GHz in Lynx. And when I decrease voltage to 1.456v, CPU's GFLOPS increases to 76-77. This is fairly significant that I get more 4-5GFLOPS, also the CPU's Integer performance increases accordingy. And Of course my CPU is perfectly stable at 1.456v, then why more voltage ?
You should try 4GHz with least voltage you can provide.
Use Lynx for stability test, set the problem/memory size to max. Try it for 10 to 20 tests at least. If it doesn't fail then your CPU is ready for 24/7 usage.
If it is stable at 4.0Ghz with lower voltage, try 4.1-4.2Ghz. And If that is stable at under 1.55volts then its ok otherwise higher voltage than 1.55 with 100-200Mhz will not give you more performance while chances of BSOD may increase up to multiple times.
What GPU are you using, most people overclock their CPU to max because they want to reduce the bottleneck in multi-gpu setup. If you are having such problems then go on otherwise you won't get any performance over 3.8-4.0Ghz in general usage. But your CPU power consumption will increase to over 220 watts at load.
ALSO, only increasing CPU core frequency will make the CPU inefficient. Try bumping up the CPU-NB frequency to max then test it. You will see huge performance increment with high CPU-NB frequency. This happens because increasing core frequency does increase the execution rate but the memory bandwidth is not always enough for those faster executions, hence you will not get max performance of your overclock. CPU-NB/L3 is the key of memory bandwidth efficiency. You increase it you get more performance. So I want you to set your CPU-NB to 2860MHz (286x10). Max CPU-NB voltage for this frequency must not be higher than 1.25-1.325volts.
Edited by sumitlian - 8/31/12 at 9:36pm