• How to force XMP enhanced memory to operate at 800 MHz on the Apple Macbook Pro 2011.

Today the most exciting memory performance is achieved with DDR3 SDRAM modules and the Intel XMP extension which has now become available on SO-SDIMM parts too. But the XMP extension is an advantage only for DRAM modules being used in systems with XMP compliant BIOS. Unfortunately, the current implementation of UEFI for the Apple MacBook does not provide any over-clocking possibilities and do not support Intel XMP. At first glance, the problem appears to be unsolvable until Apple release an update for UEFI. But if you completely read this article then you have probably already guessed about the idea we are going to share. So, the trick is to copy XMP settings into a regular SPD timing table.

The new MacBook Pro lineup lunched at the beginning of 2011 comes with the latest Intel Sandy Bridge code-named mobile processors. Today Apple equips its new PRO series laptops with a big variety of Intel Core i5 and i7 processors designed on the new architecture, but only some of them allow the integrated memory controller to operate above 667 MHz. According to the official technical documentation on Intel Core 2nd generation processors the integrated memory controller is capable of operating at a clock frequency of 800 MHz only for four mobile parts. These are quad-core processors:

*Intel Core i7-2820QM Processor (2.30 GHz)
*Intel Core i7-2720QM Processor (2.20 GHz)
*Intel Core i7-2715QE Processor (2.10 GHz)
*Intel Core i7-2710QE Processor (2.10 GHz)

As to SO-DIMM DDR3 SDRAM modules with the XMP extension, they are all programmed to meet JEDECs requirements and have a standard DDR3-1333H or DDR3-1066F speed bin. This means that DRAM controller of CPU will operate at 667 MHz or 533 MHz respectively. As of a clock frequency of 800 MHz, manufacturers still prefer not to program DDR3-1600H speed bin because of backward compatibility with previous generation Intel-based systems and AMD platforms.

So, lets take a look at the Kingston KHX1600C9S3K2/8GX DDR3-1333H SO-DIMM module featuring two XMP profiles. We are going to use it as an example for this article.

KINGSTON HYPERX Series
SO-DIMM DDR3 SDRAM Module

According to the XMP settings, the module is capable of operating at 667MHz and 800 MHz with its specific timing set. We are interested in the second Enthusiast profile which is for 800 MHz. Its settings correspond to the standard DDR3-1600H speed bin. The only minor difference is tRAS delay; it is programmed to 27T instead of 28T.

INTEL XMP 1.2 PROFILES
From SPD of the Kingston KHX1600C9S3K2/8GX 4GB Module

Besides, the module and SDRAM components do not require extra voltage and operate at nominal 1.50V. This is very good, as VDD is not adjustable within DDR3 SPD and requires to be increased to 1.65V typical for this clock frequency for most of DDR3 modules.

Now lets move to the practical part. So, our goal is to replace the existing JEDEC SPD timing table with one from the XMP profile. Lunch Thaiphoon Burner and after reading entire SPD content open DDR3 Timing Table Editor. All we need is just to go into the Profile main menu and choose Import From XMP #2.

DDR3 TIMING TABLE EDITOR
Profile main menu

Click on the Next button to move to the next step and select Reprogram SPD EEPROM with new SPD data. Before flashing make sure you have selected the proper SPD EEPROM location from the list. Click Apply to reprogram SPD. After reprogramming, if you are using Thaiphoon Burner prior to version 7.2.0.1, SPD CRC checksum needs to be corrected manually. Otherwise CRC is corrected automatically. To correct checksum close Timing Table Editor, choose Correct Checksum from the EEPROM main menu.

TIP: You may not install Microsoft Windows on a separate partition of your Macbooks hard disk before SPD flashing. Since version 7.2.0.0 Thaiphoon Burner is compatible with Windows PE. So, you can run any Windows XP or 7 Live Edition from a bootable USB flash disk or CD/DVD and perform any SPD firmware modification with Thaiphoon Burner software. You can use our tiny 37 MB in size live 32-bit Windows XP image preapared by Norton Guest to boot your Macbook from USB flash drive. The Norton Guest windows utilitity is included in the RAR package.

NOTE: NOTE: Before making any changes within SPD data array make sure the SPD EEPROM chip is not write-protected. Please be aware that all of DDR3 SDRAM SO-DIMM modules manufactured by Samsung, Hynix, Elixir/Nanya Technology, Silicon Power, Crucial Technology (SO-DIMM), Patriot (SO-DIMM) and Micron Technology are shipped with enabled Permanent Software Write Protection (PSWP) feature that does not enable the SPD EEPROM chip to be reprogrammed. To check whether your modules are write-protected call PSW Protection dialog box from Thaiphoon Burner. It is recommended to buy Kingston and Corsair DRAM modules since they come with 100% unprotected SPD EEPROMs.

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