System wont post when 8 GB installed

[UNIXman954]

Hi,

I have a situation with the first PC that I have built from scratch. I can only get it to post and run when 4 GB of memory is installed. When I add the other 4 GB that I have, the system does not post and just powers on and then off again. I am kinda new at the PC building stuff, so I was wondering if anyone has any ideas? I am thinking something in the BIOS needs to be changed, but I am not exactly sure what.

Here are my specs:

Motherboard = ASUS P5K3 Deluxe WiFi AI Lifestyle
CPU = Intel Quad Core 6850
Memory = 4 pairs of OCZ ReaperX DDR3-1333 2x2GB. System will post and run fine with 2 of these installed, but not all 4.
OS = Vista 64 bit Ultimate
Right now, the Bios is set to Standard for AI Overclocking - so I do not think I am attempting to overclock anything?

Now, mind you with these modules it is a VERY tight fit with all 4 boards installed because they are thick buggers with large heat coils attached, but it does appear to be possible to get all four inserted properly. However, when this is done, my system fails to post and just turns on and off over and over - no beeps or anything to indicate a problem.

Any thoughts would be appreciated.

Thanks,
Steve.

[Spawn_abx]

I have three suggestions found on another board:

1: Up the memory voltage to 1.8v
2: Use one stick at a time to see if you have a DOA
3: Try the rated settings

Hope It Helps!

Vince



P.S. Nice hardware!

[SRTDodge05]

1.8V is stock voltage for DDR2 with four dimms you'll want to try 1.9 or little higher. Also need to check to make sure your memory is running at the right timing. With some motherboards using four dimms and that much memory you need to run them at a lower speed. I would also check for bios update for your board.

[Ford Freak]

I would try at least 1.9v. You may need to go with 2.0 to 2.1v after looking at the voltage requirements for other OCZ RAM.

Originally Posted by SRTDodge05

1.8V is stock voltage for DDR2 with four dimms you'll want to try 1.9 or little higher. Also need to check to make sure your memory is running at the right timing. With some motherboards using four dimms and that much memory you need to run them at a lower speed. I would also check for bios update for your board.

He has DDR3.

[UNIXman954]

Hey all. Thanks for the suggestions. I finally got it to post and boot with 8 GB (four dimms) by bumping Memory Voltage up to 2.10 and NorthBridge Core Voltage up to 1.7. I do not think I was ever so happy to hear the post beep in my life.

Thanks for all your suggestions - they all guided me to the right spots in bios.

Take Care,



Steve.

[specmike]

Based on what you have posted, it's the NB Core voltage that did the trick. When you go to 4 DIMMs you are doubling the load on the NB. Based on this : OCZ Technology | Products | Memory | OCZ PC3-10666 ReaperX HPC Enhanced Bandwidth

I'd suggest you see if it will run at 1.85v Vdimm or even 1.9v since that is what they are rated for. You should not need 2.1v Vdimm to run this. It's the NB that needed the voltage bump.

[Underwater Mike]

Glad to hear your issue was solved. Hope you don't mind if I hijack your thread!

Q: When you have four sticks of that stuff plugged in, are the heatpipe coils touching each other? Also, with the coils that close together, how much air movement is possible? Do you have a fan on the RAM?

Thanks!