XMS Qualification and Testing Updated 6-20-2007
Corsair has developed a methodology in-house for developing, qualifying, and testing memory for use in over clocking applications. Some common questions about this process are answered below, and details are given for testing for specific XMS product families.
Q: What does XMS mean, and what is the idea behind it?
A: We have taken to heart a few facts that over clockers have known for years:
1) Many integrated circuits are capable of operating much faster than their specified speed
2) Standards organizations by their very nature have a difficult time keeping up with market changes.
XMS, or eXtreme Memory Speed, is the process that Corsair uses to take ICs rated at one speed and verify/guarantee their operation at another speed. Since specifications have not been generated to accurately specify operating parameters, Corsair gives these parts an XMS rating. For example, since PC2400 does not exist according to any valid standards institution, Corsair parts are called XMS2400.
Q: How do you verify operation at the XMS speed?
A: In a nutshell, through extensive evaluation in our lab. In order to offer an XMS module, a RAM must be found which can run with adequate stability in multiple platforms at the XMS-rated speed. Testing is done using both Corsairs’ stress-testing fixture, as well as by running common benchmarks, applications programs, operating systems, and games. Parts are evaluated over voltage and temperature extremes to monitor stability. No XMS part is released until all criteria are met.
Q: How do you guarantee operation at the XMS speed?
A: XMS parts are a speed screen of Corsair's standard parts. They are 100% tested at the XMS-rated speed; parts that fall out of this test are tested at the standard rated speed. For example, XMS2400 modules are 100% tested at 300 MHz. Parts that do not meet this speed grade are then tested at PC2100. Specific testing parameters for various XMS products are given below.
Q: How do you program the SPD of XMS parts?
A: Programming the SPD of our XMS parts is a bit problematic. The industry-standard specifications for the SPD values of XMS parts are often not yet defined by JEDEC (the appropriate standards organization) when the parts are introduced. In order to maintain compatibility with the multitudes of motherboards and BIOS revisions out there, the SPD values are programmed at the fastest available parameters defined by JEDEC. The SPD values are defined in the matrix below. Note, though, that in ALL CASES the Corsair part number (which contains the XMS speed grade) is programmed into the SPD as well.
Dont see your module or speed grade listed please check Archive XMS Settings
XMS DDR1
Archive XMS Settings
DDR2
DDR2 XM2S-4300C3_____Custom values for PC2-4300C3
DDR2 XM2S-5400_______Custom values for PC2-5400
DDR2 XM2S-5400UL_____Custom values for PC2-5400UL
DDR2 XMS2-5400C4_____Custom values for PC2-5400C4
DDR2 XM2S-6400C3_____EPP + JEDEC Values for PC2-6400C5
DDR2 XM2S-6400C4_____EPP + JEDEC Values for PC2-6400C5
DDR2 XM2S-6400_______JEDEC Values for PC2-6400C5
DDR2 XM2S-8000UL_____Custom values for PC2-8000UL
DDR2 XM2S-8500/C5____EPP + JEDEC Values for PC2-6400C5
DDR2 XMS2-6400C5DHX_JEDEC Values for PC2-6400C5
For Dominator DDR2 or DDR3 modules please see
Dominator Qualifications and Testing!
Q: My XMS module does not work at the rated speed in my system. Why not?
A: There are many reasons why this can happen. Let me outline a few of them:
1) There are lots of motherboards out there, and we can only realistically evaluate/qualify a handful. You may have a motherboard that simply does not over clock well.
2) There is interaction between specific RAM manufacturers and specific motherboard manufacturers. Thus, for example, while EPoX boards might work best with RAM vendor A, Soyo boards might work better with RAM vendor B. Corsair strives to find the RAM that works most universally.
3) Other system components may not be over clock able. This may include the processor, chip set, PCI bus, IDE channel, etc.
4) The demands of today’s high end graphics cards and GHz processors the quality of your power supply has become increasingly important. Make sure you power supply make and model is approved by your motherboard manufacturer and/or your CPU manufacturer.
There are many sites on the web which can give you more reasons, tell you which boards are best for over clocking. To get an idea, go to your favorite search engine and search for "over clocking guide".
Q: I do not see the specific part that I have IE: XMS3200LLPT, why not? And what is the idea behind a slightly different part#?
A: The PT at the end of the part# in this case CMX512-3200LLPT indicates the color of the heat spreader, and would be a cosmetic change! This has no bearing on the memory or settings only the color.
Please see Archive XMS Settings
*Important Note* Unless stated otherwise, all testing is done with only one module at a time.
XMS DDR1
Archive XMS Settings
XMS DDR2
Testing parameters for Twin2x1024-4300C3:
Twin2x1024-4300C3 Data Sheet
Motherboard make and model: ABIT AA8 Durramax and/or Asus P5AD2 Premium
Each pair is tested and packaged together using the following settings:
CPU External Frequency: Manually set to 200MHz
DDR2 SDRAM Clock: Manually set to 533MHz
DRAM Timing Selectable: Auto Yields the following timings
SDRAM CAS Latency: 3T
SDRAM RAS to CAS Delay (tRCD): 3T
SDRAM Row Precharge (tRP): 3T
SDRAM Active to Precharge Delay (tRAS): 8T
DDR2 SDRAM Voltage: 1.9
NB Voltage 1.9 Volts (On Abit AA8 Only)
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts
Testing parameters for Twinx/XMS2-5400C4:
CM2X256-5400C4 Data Sheet
CM2X512-5400C4 Data Sheet
TWIN2X1024-5400C4 Data Sheet
Motherboard make and model: ABIT AA8 Durramax and/or Asus P5AD2 Premium
Each pair is tested and packaged together using the following settings:
CPU External Frequency: Manually set to 250MHz
DDR2 SDRAM Clock: Manually set to 533MHz
DRAM Timing Selectable: Auto Yields the following timings
SDRAM CAS Latency: 4T
SDRAM RAS to CAS Delay (tRCD): 4T
SDRAM Row Precharge (tRP): 4T
SDRAM Active to Precharge Delay (tRAS): 12T
DDR2 SDRAM Voltage: 1.9
NB Voltage 1.9 Volts (On Abit AA8 Only)
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts
Testing parameters for Twinx/XMS2-5400UL:
Twin2x1024-5400UL Data Sheet
Testing parameters for CM2X512A-5400UL:
Twin2x1024-5400UL Data Sheet
Motherboard make and model: Asus P5AD2-E Premium
Each pair is tested and packaged together using the following settings:
AI Over Clock Tuner: Manual
CPU External Frequency: Manually set to 226MHz
DDR2 SDRAM Clock: Manually set to 678MHz
PCI Express Freq: Auto
PCI Freq: 33.33
Performance Mode: Standard
DRAM Timing Selectable: Manual
SDRAM CAS Latency: 3T
SDRAM RAS to CAS Delay (tRCD): 3T (Revised 6/27/2005)
SDRAM Row Precharge (tRP): 2T
SDRAM Active to Precharge Delay (tRAS): 8T
SDRAM Write Recovery Time: 4
DDR2 SDRAM Voltage: 2.1
Chipset Core Voltage: 1.7 Volts
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts
Testing parameters for Twinx/XMS2-6400C3:
Twin2x2048-6400C3 Data Sheet
Motherboard make and model: Asus M2N32-SLI Premium/Deluxe
Each pair is tested and packaged together using the following settings:
AI Over Clock Tuner: Manual
CPU External Frequency: Manually set to 200MHz
DDR2 SDRAM Clock: Manually set to 800MHz
PCI Express Freq: Auto
PCI Freq: 33.33
DRAM Timing Selectable: Manual
SDRAM CAS Latency: 3T
SDRAM RAS to CAS Delay (tRCD): 4T
SDRAM Row Precharge (tRP): 3T
SDRAM Active to Precharge Delay (tRAS): 9T
SDRAM Write Recovery Time: 5
Command Rate: 2T
DDR2 SDRAM Voltage: 2.1 V
Advanced voltage control
CPU Vcore offset:_Disabled
DDR2 Termination: 0.5x
CPU to NB HT:____1.200V
NB to SB HT:_____AUTO
NB Core/PCI-E:___AUTO
SB Core/PCI-E:___AUTO
SB Standby core:_+1.500V
Output driver control
CKE:______AUTO
CS/ODT:__1.00X
ADD/CMD:_1.00X
MEMCLK:__1.00X
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts
Testing parameters for Twinx/XMS2-6400C4:
Twin2x2048-6400C4 Data Sheet
Motherboard make and model: Asus P5WD2 or M2N32-SLI Premium/Deluxe
Each pair is tested and packaged together using the following settings:
AI Over Clock Tuner: Manual
CPU External Frequency: Manually set to 200MHz
DDR2 SDRAM Clock: Manually set to 800MHz
PCI Express Freq: Auto
PCI Freq: 33.33
Performance Mode: Standard
DRAM Timing Selectable: Manual
SDRAM CAS Latency: 4T
SDRAM RAS to CAS Delay (tRCD): 4T
SDRAM Row Precharge (tRP): 4T
SDRAM Active to Precharge Delay (tRAS): 12T
SDRAM Write Recovery Time: 5
Write to Precharge Delay: 15 (If it's Listed)
Command Rate: 2T
DDR2 SDRAM Voltage: 2.1
Advanced voltage control
CPU Vcore offset:_Disabled
DDR2 Termination: 0.5x
CPU to NB HT:____1.200V
NB to SB HT:_____AUTO
NB Core/PCI-E:___AUTO
SB Core/PCI-E:___AUTO
SB Standby core:_+1.500V
Output driver control
CKE:______AUTO
CS/ODT:__1.00X
ADD/CMD:_1.00X
MEMCLK:__1.00X
Chipset Core Voltage: Auto
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts
Testing parameters for Twinx/XMS2-6400:
Twin2x1024A-6400 Data Sheet
Twin2x2048-6400 Data Sheet
Motherboard make and model: Asus M2N32-SLI Premium/Deluxe
Each pair is tested and packaged together using the following settings:
AI Over Clock Tuner: Manual
CPU External Frequency: Manually set to 200MHz
DDR2 SDRAM Clock: Manually set to 800MHz
PCI Express Freq: Auto
PCI Freq: 33.33
Performance Mode: Standard
DRAM Timing Selectable: Manual
SDRAM CAS Latency: 5T
SDRAM RAS to CAS Delay (tRCD): 5T
SDRAM Row Precharge (tRP): 5T
SDRAM Active to Precharge Delay (tRAS): 12T
SDRAM Write Recovery Time: 5
Write to Precharge Delay: 15 (If it's Listed)
Command Rate: 2T
DDR2 SDRAM Voltage: 1.9
Advanced voltage control
CPU Vcore offset:_Disabled
DDR2 Termination: 0.5x
CPU to NB HT:____1.200V
NB to SB HT:_____AUTO
NB Core/PCI-E:___AUTO
SB Core/PCI-E:___AUTO
SB Standby core:_+1.500V
Output driver control
CKE:______AUTO
CS/ODT:__1.00X
ADD/CMD:_1.00X
MEMCLK:__1.00X
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts
Testing parameters for Twinx/XMS2-8000UL:
Twin2x1024-8000UL Data Sheet
Motherboard make and model: Asus P5WD2 Premium/Deluxe
Each pair is tested and packaged together using the following settings:
AI Over Clock Tuner: Manual
CPU External Frequency: Manually set to 250MHz
DDR2 SDRAM Clock: Manually set to 1000MHz
PCI Express Freq: Auto
PCI Freq: 33.33
CPU Core Voltage: Auto
FSB Termination V: 1.5 Volts
MCH Chiset V: 1.65 Volts
ICH Chiset V: 1.20 Volts
Performance Mode: Standard
DRAM Timing Selectable: Manual
SDRAM CAS Latency: 5T
SDRAM RAS to CAS Delay (tRCD): 4T
SDRAM Row Precharge (tRP): 4T
SDRAM Active to Precharge Delay (tRAS): 9T
SDRAM Write Recovery Time: 5
DDR2 SDRAM Voltage: 2.2
Chipset Core Voltage: Auto
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts, However this DDR2 module would be the only one rated at 2.2 Volts Max.
Testing parameters for Twinx/XMS2-8500/C5:
Twin2x1024-8500 Data Sheet
Twin2x2048-8500C5 Data Sheet
Motherboard make and model: Asus M2N32-SLI Premium/Deluxe
Each pair is tested and packaged together using the following settings:
AI Over Clock Tuner: Manual
OC Operation: Disabled
NOS Operation: Disabled
CPU External Frequency: Manually set to 268 MHz
PCI CLK1: Auto
PCI CLK2: Auto
DDR2 Voltage control: 2.200V
CPU Core Voltage: Auto
CPU Multiplier: 10
DDR2 SDRAM Clock: Manually set to 800MHz
DRAM Timing Selectable: Manual
SDRAM CAS Latency: 5T
SDRAM RAS to CAS Delay (tRCD): 5T
SDRAM Row Precharge (tRP): 5T
SDRAM Active to Precharge Delay (tRAS): 15T
SDRAM Write Recovery Time: 5
1T/2T: 2T
A1 Clock Skew: Auto
Advanced voltage control
CPU Vcore offset:_Disabled
DDR2 Termination: 0.5x
CPU to NB HT:____1.200V
NB to SB HT:_____AUTO
NB Core/PCI-E:___AUTO
SB Core/PCI-E:___AUTO
SB Standby core:_+1.500V
Output driver control
CKE:______AUTO
CS/ODT:__1.00X
ADD/CMD:_1.00X
MEMCLK:__1.00X
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts, However this DDR2 module would be the only one rated at 2.2 Volts Max.
DDR2 XMS2DHX
Testing parameters for TWIN2X/XMS2-6400:
Twin2x2048-6400C5DHX Data Sheet
Motherboard make and model: Asus M2N32-SLI Premium/Deluxe
Each pair is tested and packaged together using the following settings:
AI Over Clock Tuner: Manual
CPU External Frequency: Manually set to 200MHz
DDR2 SDRAM Clock: Manually set to 800MHz
PCI Express Freq: Auto
PCI Freq: 33.33
DRAM Timing Selectable: Manual
SDRAM CAS Latency: 5T
SDRAM RAS to CAS Delay (tRCD): 5T
SDRAM Row Precharge (tRP): 5T
SDRAM Active to Precharge Delay (tRAS): 15T
SDRAM Write Recovery Time: 5
Write to Precharge Delay: 15 (If it's Listed)
Command Rate: 2T
Advanced voltage control
CPU Vcore offset:_Disabled
DDR2 Termination: 0.5x
CPU to NB HT:____1.200V
NB to SB HT:_____AUTO
NB Core/PCI-E:___AUTO
SB Core/PCI-E:___AUTO
SB Standby core:_+1.500V
Output driver control
CKE:______AUTO
CS/ODT:__1.00X
ADD/CMD:_1.00X
MEMCLK:__1.00X
DDR2 SDRAM Voltage: 1.9
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts
Testing parameters for TWIN2X4096-6400C5DHX:
Testing parameters for QUAD2X4096-6400C5DHX:
TWIN2X4096-6400C5DHX Data Sheet
QUAD2X4096-6400C5DHX Data Sheet
Motherboard make and model: Asus M2N32-SLI Premium/Deluxe
Each pair is tested and packaged together using the following settings:
AI Over Clock Tuner: Manual
CPU External Frequency: Manually set to 200MHz/(266Mhz for Intel)
DDR2 SDRAM Clock: Manually set to 800MHz
PCI Express Freq: Auto
PCI Freq: 33.33
Performance Mode: User Define/Manual
DRAM Timing Selectable: Manual
SDRAM CAS Latency: 5T
SDRAM RAS to CAS Delay (tRCD): 5T
SDRAM Row Precharge (tRP): 5T
SDRAM Active to Precharge Delay (tRAS): 15T
SDRAM Write Recovery Time: 5
Write to Precharge Delay: 15 (If it's Listed)
Command Rate: 2T
DDR2 SDRAM Voltage: 1.9
Advanced voltage control
CPU Vcore offset:_Disabled
DDR2 Termination: 0.5x
CPU to NB HT:____1.200V
NB to SB HT:_____AUTO
NB Core/PCI-E:___AUTO
SB Core/PCI-E:___AUTO
SB Standby core:_+1.500V
Output driver control
CKE:______AUTO
CS/ODT:__1.00X
ADD/CMD:_1.00X
MEMCLK:__1.00X
Chipset Core Voltage: Auto
All other settings are motherboard defaults.
Maximum DDR2 recommended VDIMM: 2.1 Volts
