How Do I Set DRAM To Run To Spec?
To answer this question, we’ll have to break it into AMD and Intel. We’ll take a look at Intel first.
Setting up DRAM on Intel rigs is fairly straightforward and easy (most of the time). Usually, there is DRAM that runs at less than 1600 MT/s and DRAM that runs at rates higher than 1600. Check your manual for the preferred slot selections (usually slot one/three or two/four on dual-channel motherboards), and look to see whether the slots are color-coded. With DRAM 1600 and up (with a few exceptions), you get XMP profiles in the SPD of the DRAM. With XMP DRAM, you simply enter the BIOS, enable XMP and select Profile 1. Depending on the actual XMP settings, you can try Profile 2 for a slight performance boost.
If there are any problems, try the following steps:
- Make sure you have the latest BIOS.
- Ensure your CPU is capable of running the frequency/data rate. If both of these requirements are met but the memory isn’t stable, a small increase in DRAM voltage or MC voltage might be needed. On Intel, I usually suggest about +5mV (0.005V) to either the DRAM voltage, the MC voltage or both. To locate the MC voltage, look for something like CPUVTT, DDRVTT, QPI/VTT or VCCIO. Some motherboards incorporate the MC voltage into the system agent voltage or VCCSA; this is seen most often in LGA 2011. Exercise caution by checking to see what other users have found to be safe and beneficial.
- If automatic configuration methods like XMP aren’t available, you can attempt to manually set the timings and voltages to rated levels.
- You can also check with the DRAM manufacturer (your best bet) or ask in the forums. We have many knowledgeable members and some DRAM tech reps, and I’m there daily.
AMD setup involves a few minor differences. Whereas with Intel, you look for XMP in the BIOS, an AMD platform without an explicit XMP setting might still have DOCP, EOCP or AMP. These are all ways to enable auto DRAM setup.
DOCP, EOCP and XMP on AMD appear to read the Intel XMP data from the SPD and then apply what the BIOS programmer considers best for a given AMD frequency, which often can be a bit looser than the specifications of the DRAM.
The same steps can be implemented for troubleshooting. Make sure you have the latest BIOS, and with AMD in particular, make sure your CPU can run the frequency/data rate. With AMD, it's much more common to have to add voltage to the DRAM and/or the MC (usually the CPU/NB voltage on AMD motherboards).