I have been happy running Boinc for a few weeks and had no problems.

Today I went in Boinc manager and changed from using 20% cpu to 100% to speed up the climate predict task.

On doing so my computer crashed straight to blue screen of death it saved some crash log and locked up.

I restarted my computer after pulling power lead out socket and waiting a few minutes.

Now when I startup - just motherboard led lights up, cpu fan is not rotating as if its dead :(.

This is a brand new system about 3 weeks old

specs:
Intel 3rd Generation Core i7-3770K CPU (4 x 3.50GHz, Ivy Bridge, Socket 1155, 8Mb L3 Cache, Intel Turbo Boost Technology 2.0)

Corsair CMZ16GX3M4A1600C9B 16GB (4x4GB) 1600MHz CL9 DDR3 Vengeance Blu Memory
Asus P8Z77-V PRO Motherboard
OCZ AGT3-25SAT3-120G Agility 3 120GB SATA III 2.5 inch SSD

Asus nVIDIA GeForce GTX 550 Ti Graphics Card

Microsoft Windows 7 Home Premium, Full Version 64 bit

using latest drivers as i know of.

no overclock - standard speed
I reset memory using 'mem ok' - no change

any help would be great

Can boinc really damage my PC ?

What Power Supply are you using? It's the most important thing you haven't mentioned.

Claggy

it is generic 750 watt.

I just tested with a dedicated power supply tester all ok.

stable voltages

here are the test results :

-12v = 11.7 12.L
5VSB = 5.1
PG = 280 ms
+5v = 5.0
+12v1 = 12.0
+3.3v = 3.4

CIT Pentium P4 750U, 750W

What cooling do you have?, Is it a Stock cooler, or Heavy duty aftermarket job?

Have you been monitoring temperatures?

When you said you changed a preference from 20% to 100%, was that for the 100% of CPUs to be used, or for 100% of CPU time to be used (this preference is only really used to limit temperatures if the cooling is marginal)

Does the PC now boot now it's cooled down (I've had this problem when my H80 wasn't circulating properly)

Claggy

I have stock cooler. 2 weeks ago, with BOINC on 100% for 3 hours cpu temp never got above 48 C.

I think it was 100% of the cpu to be used. Im not sure.
simple mode.

Tools -> computer prefs , gen prefs -> then 2/3 down, a combo/listbox for cpu selection changed to 100%. then crash.

After the crash I did restart once, so maybe the power on button is faulty.