Just joined, busy with building and firing up my new rig on a GA-Z87X-UD7-TH Mobo, i7-4770k CPU (de-lidded), 32 Gig Corsair RAM, WIN 7 Pro 64-bit, and have been getting a 51 Debug Message any time I try to get away from the BIOS Optimized Default settings.
Tried all the usual trouble-shooting procedures short of replacing Mobo and RAM.
Checked connectors and voltages with a probe-meter, all look good.
Prime95, memtest86, and AIDA-64 torture-test run for many hours without complaint or error.
Since BIOS version on Mobo was F2, decided to try updating to F4, which Gigabyte site says is current, stable version for the UD7-TH.
Q-flash refused to proceed, telling me that F4 version from Gigabyte site was "obsolete".
Gigabyte Tech support had me install an undocumented utility called AppCenter, then use @bios to install the F4 BIOS version, which worked.
Rebooted into BIOS, loaded Optimized Defaults at Tech Support's direction.
51 message gone, replaced by AE or A6 message (not surprised by that, the ASUS BD-burner and BDROM/DVD/CD-burner show up as SCSI devices, even though they are connected as SATA and work as they should). Perhaps newer drivers for the optical drives will fix that.
Rebooted into BIOS, found memory timings at 9-9-9-24 and 1333 mhz.
Changed to 10-10-10-27 @ 1600 mhz, 51 message came back.
Fighting ghosts, or is this a problem?
Gigabyte Tech Support had no answer, as of yesterday.
Other than that, I love this rig, it absolutely flies with Bryce 7, TrueSpace 7.6, Silo, and Photoshop, and I haven't really gotten into OC-ing yet.