Can't get Z420 to read compatible RAM

[StonewallJackso]

Hi all,

I have an HP Z420 with Windows 7 Professional 64-bit. It came with 4GB of RAM already installed, and I wanted to upgrade to 8GB. So I bought two sticks of 4GB RAM, making sure it was compatible (PC3 12800E) and the same brand as what came with the computer.

I replaced the two 2GB sticks with the 4GB sticks in the same slots, and the computer still only reads 4GB of memory.

Here are the computer's memory specifications:

8 DIMM slots, Up to 64 GB ECC unbuffered DDR3 1600 MHz; 4 channels per CPU

Could someone please help me figure this out?

Thanks in advance.

[banhien]

Hi,

Please try these steps:

Hold down the Windows Key and press R (or just Click Start),
Type msconfig in the Run box (or Search box) and hit Enter,  
In the System Configuration windows, click the Boot tab,
Click the Advanced Options button,
Un-stick the box next to 'Maximum Memory',  
Click OK,
Click Apply and then OK to get out,
Restart the notebook for the change to take effect.

Regards,

[StonewallJackso]

Hi, and thanks for the response. I had already tried this, but I went through the process again to make sure, and it still says that only 4GB are installed when I have 8GB in the slots.

[Big_Dave]

Hi,

Boot into the BIOS and tell us how much memory is detected.

[StonewallJackso]

In the BIOS it says:

Memory Size: 4GB ECC UDDR3 / 1600 MHZ

Not sure if this is relevant, but it also shows UDIMM1 through UDIMM8. After UDIMM6 and UDIMM8 it says 2.

[Big_Dave]

Hi, 

Does your PC have dual physical processors?

[StonewallJackso]

Yeah, it does. I'm reinstalling Windows 7 right now in case that does anything. Otherwise, I'm stumped.

[Big_Dave]

Hi, If you are not running W7 Pro or higher then windows 7 is not going to support dual physical processors. Review your dimm installations. If you only have two dimms then be sure that each dimm is in the same dimm slot that is associated with each processor.

[mdklassen]

> Could someone please help me figure this out?

Three possibilities:

1. Given that the motherboard claims to have EIGHT slots for RAM, it's possible that the motherboard supports a maximum of only 2GB per slot, even though your RAM is labelled '4GB'.
2. Your RAM is a 4GB "pair", namely two certified-identical 2GB sticks, totalling 4GB.
3. Your motherboard only supports "low-density" RAM, not "high-density" RAM.  Count the number of large "chips" on your original RAM, and count the number of large "chips" on the new RAM.  If the count is the same, you have replaced "low-density" RAM with "high-density" RAM.  

What is shown in the BIOS-SETUP when both the "old" and the "new" sticks are installed?  How many of those 'UDIMM' lines are reported?

From: http://h20195.www2.hp.com/V2/GetPDF.aspx/4AA4-0128ENUC.pdf

>>> Bring power and performance to the next level with the all new E5-1680 v2 8-core processor ,,,

Yes, 8 cores, like a high-end Intel i7 CPU.

>>> Support up to 64GB of the latest generation of system memory with 8 DIMM slots

>>> and integrated DDR3-1866 (Transfer rates up to 1866 MT/s) memory subsystem.

So, it supports up to 8GB per slot, if you use the correct RAM.

>>>  10. Although the Intel Xeon E5-2600 processor family supports dual processors, the HP Z420 Workstation does not support dual processor configurations.

Thus, you do *NOT* have two physical CPUs.

[Big_Dave]

Was @StonewallJackso caught posting bad information?