OP, while you were in the BIOS setup program, did you try the F1 key to invoke 'General Help' and the look for 'Advanced BIOS features'?
Which BIOS version does your motherboard have?
Which CPU do you have?
AMD Athlon 64 X2 4000+ 2000MHz 1MBx2 Windsor 90nm F2 89W 2000 F1
AMD Athlon 64 X2 4000+ 2000MHz 1MBx2 Windsor 90nm F2 65W 2000 F1
AMD Athlon 64 X2 4000+ 2100MHz 512KBx2 Brisbane 65nm G1 65W 2000 F2
AMD Athlon 64 4000+ 2600MHz 512KB Orleans 90nm F3 62W 2000 F1
GA-M61SME-S2 (rev. 2.x) CPU support list
http://www.gigabyte.com/products/product-page.aspx?pid=2507#I don't see any way of enabling Virtualization:
*m61sme-s2_2002_i.p65 - motherboard_manual_ga-m61sme-s2_2.0_e.pdf
http://download1.gigabyte.us/Files/Manual/motherboard_manual_ga-m61sme-s2_2.0_e.pdfGIGABYTE - Motherboard - Socket AM2 - GA-M61SME-S2 (rev. 2.x)
http://www.gigabyte.com/products/product-page.aspx?pid=2507#manual--
However...
A BIOS update may enable virtualization:
According to the GA-M61SME-S2 Motherboard Layout pictured in its manual, there is only one BIOS chip on the GA-M61SME-S2 (rev. 2.x). Thus if a BIOS update fails (due to a power blackout or a system crash etc) then it's bye-bye 'board.
Therefore if you DO decide to try the following please MAKE SURE that...
1) your motherboard is indeed a GA-M61SME-S2 (rev. 2.x) (you were unclear in identifying your CPU model)
2) your motherboard's current BIOS version is older than version F10A Beta - the final BIOS version available for the GA-M61SME-S2 (rev. 2.x)
3) you download and THOROUGHLY READ the manual for your motherboard in order to learn how to safely flash the BIOS
4) before flashing the BIOS, you go into the BIOS setup and "Load Fail-Safe Defaults" and then "Save to CMOS and EXIT (Y/N)? Y"
5) you update the BIOS via Q-Flash (see page 54 of the *manual for instructions on how to use Q-Flash)
6) you consider doing what I do before updating a BIOS (in order to minimize the chance of something going wrong): remove all unnecessary expansion cards and disconnect all needless peripherals and additional hard drives and then make sure the AC cord is securely plugged in at both ends (don't laugh)
7) after updating the BIOS you shut the PC down, disconnect the AC cable, wait a few minutes and then clear the CMOS before booting up again into the BIOS setup and choosing "Load Optimized Defaults" followed by "Save to CMOS and EXIT (Y/N)? Y".
"Problem solved with Gigabyte GA-M61SME-S2 motherboard by flashing the BIOS
with F10a update - you then get in "Advanced BIOS features" the first
option of "Virtualization" as enabled (not actually an option but
permanently enabled).
Go to http://uk.gigabyte.com/products/product-page.aspx?pid=2507&dl=1#biosand
download version F10a. You get
motherboard_bios_ga-m61sme-s2_2.0_f10a.exe which self extracts in a windows
machine. I took the bios file M61SMES2.F10a and updated the bios on my
linux machine using Q-Flash utility found when you go into the bios system
(press del on start up)"AM2 motherboards with HVM support | Xen | Users
http://www.gossamer-threads.com/lists/xen/users/236762--
FWIW I used to have an Athlon64 x2 4600+ (2.4GHz) with 8GB of 800MHz RAM running on a...
ASUS M3A78-EMH HDMI
http://www.asus.com/Motherboards/M3A78EMH_HDMI/...and its virtualization performance wasn't worth much.