I have a GA Z87X-UD5H motherboard. I recently bought two modules of 16GB ram (total of 32GB in two sticks). The ram is 16GB DDR3 1600Mhz Reg ECC (Samsung M393B2G70BH0-CK0).

The boot does not go past code 15 Pre-memory North-Bridge initialization is started. (from the manual)

I've read that some boards only support 8gb per slot. Is this my case? The CPU i7-4770k supports much more RAM than the motherboard makes available however.

From the manual, the motherboard supports:

4 x 1.5V DDR3 DIMM sockets supporting up to 32 GB of system memory * Due to a Windows 32-bit operating system limitation, when more than 4 GB of physical memory is installed, the actual memory size displayed will be less than the size of the physical memory installed. Dual channel memory architecture Support for DDR3 1600/1333 MHz memory modules Support for non-ECC memory modules Support for Extreme Memory Profile (XMP) memory modules (Go to GIGABYTE's website for the latest supported memory speeds and memory modules.)

What is the compatibility issue with the RAM, and would any 16GB module work with this board?

Thanks so much for your time.

1 Answer 1


You bought registered and ECC RAM.

Your motherboard and CPU expect unregistered and non-ECC RAM.

  • Registered RAM will not work in board that expects unregistered.

  • ECC RAM may or may not work in a board that expects non-ECC, but even if it works it won't be in ECC mode.

Basically, your RAM is not supported by your system. You need to buy unregistered ("normal") non-ECC RAM. (If you happen to have unregistered ECC RAM lying around you can try it, but it won't be in ECC mode anyway and there's a chance of incompatibility so don't go and buy any new.)

Generally, registered memory and ECC are considered special features, so will be called out explicitly in product descriptions. If they are not mentioned then you can probably assume the product is 'normal'.

While most RAM listed as DDR3 (without "registered") should work, your best bet if you want 100% certainty is to look at the memory support list provided by your motherboard manufacturer, as these are the ones they have tested. However, this will likely be the more expensive option, and being on that list is by no means a requirement for compatibility. Most PC builders and enthusiasts don't bother with these lists.

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