I have intel desktop motherboard DH61WW,I am facing blue screen error while using one ram in each two slot.When I use only one ram any of the two I don't face any issue but two rams together cause blue screen errors at least once a day.I have also run memory diagnosis tool but it don't show any error
You are putting the two DIMMs into the blue DIMM slots, right?
What is your definition of a memory diagnosis tool? If you are talking about the one built in Windows, it is useless. I suggest you download and use something like MemTest86+.
Ok, the possibilities are a problem with the board (which could be problem with BIOS; see next point), a problem with the processor (its memory controller(s)) or a problem with the memory.
If you are not running the latest available BIOS (BE0120) for your board, then you need to upgrade the BIOS to this version and then test again.
Note that there are special instructions that you must follow to upgrade this BIOS. See the Release Notes for the details.
Here is link to BIOS Release Notes: https://downloadmirror.intel.com/23393/eng/BE_0120_ReleaseNotes.pdf.
Here is link to BIOS download page: https://downloadcenter.intel.com/download/23393/BIOS-Update-BEH6110H-86A-?product=54876.
There are links on this page that you can use to get to the download pages for previous versions of this BIOS.
Here is link to information regarding BIOS update process: http://www.intel.com/content/www/us/en/support/boards-and-kits/desktop-boards/000005547.html.
Here is link to additional information regarding the BIOS Recovery process: http://www.intel.com/content/www/us/en/support/boards-and-kits/000005630.html?wapkw=bios+recovery.
Once you are on the latest available BIOS, test again. If the problem persists, then the next step is to download and thoroughly test your memory with MemTest86+.
Hope this helps,