Hello, I'm Jewel with Kingston Technical Support and would like to offer our assistance. The ASRock G41M-GS3 is only compatible with memory modules up to 4GB running at 1066 (1333 Overclocking). The HyperX modules run at 1333Mhz 1.5V standard without changing any settings and typically should down clock based on what the system requires. If the memory is not being recognized at all, causing no POST, then changing the memory timings does not usually make a difference. Verify that your BIOS is up to date as I found the latest version 1.30 dated 1/17/2011 says "Patch DDR3 8GB Memory for onboardshare memory." (http://www.asrock.com/mb/Intel/G41M-GS3/?cat=Download&os=BIOS) There is also chance if this is a newer set of memory that these modules are single rank which could make them incompatible with your system. We can determine that based on the revision number on the module. Please call us at 1-800-435-0640 (USA and Canada only) M - F 6am - 6pm PT and I or another available Technician will assist you. Please be sure to have the part in question on hand when you call.
Thank you for selecting Kingston as your upgrade partner.