There is no for Windows but it is in Grub2 - WRMSR command I just don't know what registry address to change the bit 26 SSE2:
I also found a msr-cmd.exe tool for Windows but I don't know how to use it to edit bit 26 SSE2:
Usage:
msr-cmd.exe [options] read <reg>
msr-cmd.exe [options] write <reg> <edx(63~32)> <eax(31~0)>
msr-cmd.exe [options] -l write <reg> <hex_val(63~0)>
msr-cmd.exe [options] rmw <reg> <h bit> <l bit> <unmasked_hex_val>
msr-cmd.exe [options] rmwmask <reg> <mask(63~0)> <unmasked_hex_val>
msr-cmd.exe [options] getbit <reg> <#bit>
msr-cmd.exe [options] setbit <reg> <#bit> <0/1>
Options:
-s write only do not read back
-d data only, not to print column item name
-g <GRP> processor group (default: 0) to apply
'A' or 'a' to apply to all available processors groups
by default, a group can contain up to 64 logical processors
However, I modified another - IA32_CLOCK_MODULATION 0x19A register without any problems in GRUB2:
wrmsr 0x19a 0x12
or under WinXP 64-bit with msr-cmd.exe:
msr-cmd read 0x19a
msr_read(): CPU 0 reg: 0x0000019a edx: 0x00000000 eax: 0x00000002
msr-cmd write 0x19a 0x00000000 0x00000012
msr_write(): ret: CPU 0 reg: 0x0000019a edx: 0x00000000 eax: 0x00000012