It was recommended by Intel support that I remove the BIOS battery and reset the BIOS settings to their default, which I did today. I will have to see what happens, but given that it is an intermittent issue, hard to say if and when. One other problem that I failed to mention is that three times in the past couple of months, when coming to the Windows 7 login screen, my USB keyboard failed to work and I had to reboot the system because I could not enter the login password.
First, let me state that I have built 2 reasonably high performance AMD Desktop PCs in the last year or two and many general purpose Intel desktop PCs over the years. I have never run into this issue before.
I get the post "21" error under all phases of system building.
Building from the ground up, I get the post 21 error when I install each of the following components, in order (in and out of the case):
Intel Core I7 - 875K 2.94Ghz Unlocked LGA 1156 CPU
OCZ 8B DDR3 PC10666 1333MHZ 8192MB (2 X 4GB)
ATI FIREPRO V7750 1GB PCIE 2.0 X16
That it. Code 21 each and everytime I give the MB power from a ULTRA X4 750W power supply modular.
Tech support was not able to resolve my POST 21 error. However, my problem is different than yours, because it happens to me intermittently, not every time. When I do get a POST 21, immediately power cycling the computer allows the motherboard to start normally the next time. I recently updated the BIOS again to the latest (5531), and I am going to wait and see if that helped.
Good idea. I always select tested components when building a new system because it eliminates another source of problems if troubleshooting is necessary. From what little gain that may be had from a high performance non-tested component, it is just not worth the hassle.
I am currently using 8 GB of tested Kingston memory.
The exact memory is KVR1333D3N9K2/4G. That is a 4GB kit (A quantity of two ram sticks at 2GB each for a total of 4GB). Therefore I ordered two kits because I wanted a total of 8GB ram.
Intel's list of tested memory is some times old or incomplete, so if you go to the manufacturer of the memory and plug in the motherboard model, a more complete list can be generated, specifically the various different kits that are available. I still double check the specs to insure that the speed, etc. are correct as listed on the Intel site.
Although it may be a coincidence that you are both using OCZ memory, and the memory may or may not be the cause of your problems, but did you verify that you are using tested and/or certified memory for the DP55KG? Intel shows no tested OCZ memory, and the OCZ web site only lists the following part numbers as being approved for the DP55KG motherboard:
NOTE: SCROLL THE FOLLOWING PAGE OVER TO GET THE PART NUMBERS:
OCZ Technology Part No.
512MB, 1066MHz, DDR3-1066 PC3-8500, 240p DIMM, 1.5v
512MB, 1333MHz, DDR3-1333 PC3-10600, 240p DIMM, 1.5v
512MB, 1600MHz, DDR3-1600 PC3-12800, 240p DIMM, 1.5v
1GB, 1066MHz, DDR3-1066 PC3-8500, 240p DIMM, 1.5v
1GB, 1333MHz, DDR3-1333 PC3-10600, 240p DIMM, 1.5v
1GB, 1600MHz, DDR3-1600 PC3-12800, 240p DIMM, 1.5v
2GB, 1066MHz, DDR3-1066 PC3-8500, 240p DIMM, 1.5v
2GB, 1333MHz, DDR3-1333 PC3-10600, 240p DIMM, 1.5v
2GB, 1600MHz, DDR3-1600 PC3-12800, 240p DIMM, 1.5v
4GB, 1066MHz, DDR3-1066 PC3-8500, 240p DIMM, 1.5v
4GB, 1333MHz, DDR3-1333 PC3-10600, 240p DIMM, 1.5v
4GB, 1600MHz, DDR3-1600 PC3-12800, 240p DIMM, 1.5v
Another problem that I came across looking at other the brands of memory that are popular with overclocking enthusiasts, is that some of them exceeded the maximum voltage as noted below in bold from the Intel Web site:
The Desktop Board supports the following memory:
Four 240-pin Double Data Rate 3 (DDR3) SDRAM Dual Inline Memory Module (DIMM) connectors with gold-plated contacts arranged in two channels
1600/1333/1066 MHz DDR3 SDRAM interface
Support for single- and dual-channel memory interleaving
Non-ECC DDR3 memory
Serial Presence Detect (SPD) memory only
Up to 16 GB maximum total system memory
Unbuffered, non-registered single- or double-sided DIMMs with a voltage rating of 1.65 V or less.
Using a DIMM with a voltage rating higher than 1.65 V may damage the processor.
I purchased my barebones system from a well known on line computer retailer and therefore I assumed that all the components of the system would work together. I got a RMA for the OCZ memory, purchased the Kingston memory and I am good to go. Unfortunately, when I try to install my 64 bit version of Windows 7, the PC reboots just after the preliminary installation software is loaded and changes over to Starting Window. This is the subject of my next post but I'm not sure where to post it.