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DDR Memory Analysis. Part 4: Corsair DDR2 Modules

October 18, 2004




We proceed with a new series of articles devoted to the low level analysis of the most important characteristics of memory modules using our RightMark Memory Analyzer test package. The purpose of this analysis is to provide information on compatibility of a given memory module from a given manufacturer with different mainboards based on various chipsets. The object of our next analysis is a matched pair of DDR2 Corsair modules totaling 1 GB.

Manufacturer Information

Module manufacturer: Corsair Memory
Chip manufacturer: Micron Technology, Inc.
Web site of the module manufacturer: http://www.corsairmemory.com/corsair/xms2.html
Web site of the chip manufacturer: http://www.micron.com/products/dram/ddr2sdram/

Module Appearance

Photo of the memory module




Photo of the memory chip




Part Numbering System of Modules and Chips




Module Part Number Expansion

The brief technical documentation for this type of DDR2 Corsair memory modules (http://www.corsairmemory.com/corsair/products/specs/twin2x1024-5400c4.pdf) does not provide information on the expansion of some part number components. Nevertheless, the part numbering system of Corsair modules is rather simple and is easy to decipher on one's own.

Field Value Expansion
0 CM Manufacturer: CM = Corsair Memory
1 2X Module type: 2X = DDR2
2 512 Capacity of one module: 512 MB
3 5400 Theoretical throughput of the module: 5400 MB/sec (675 MHz)
4 C4 CAS# Latency: 4

Out of additional technical characteristics of the modules we should note the recommended 1.9 V voltage, which exceeds the voltage noted in the official specification of JEDEC (1.8 V), as well as the recommended 4-4-4-12 timings, which (as the documentation claims) are written in the SPD module chip.

Chip Part Number Expansion

FBGA code Part Number
D9BQM MT47H32M8BP-37E

As we have previously noted, due to space limitations FBGA-packaged Micron memory chips used in Kingmax DDR2 modules have an abbreviated part marking that is different from the part number. You can decode an abbreviated part marking of any Micron memory chip into a part number at http://www.micron.com/decoder/

Field Value Expansion
0 MT Manufacturer code:
MT = Micron Technology
1 47 Product family:
47 = DDR2
2 H Process technology:
H = SSTL 1.8V VDD CMOS
3 32M8 Device number: 256Mbit (32Mbit x8)
4   Device version (n/a)
5 FP Package code:
FP = lead plating, FBGA, 60-pin 8x12
6 -37E Access/cycle time:
-37E = 3.75 ns (266.7 MHz), 4-4-4
7   Special options (n/a)
8   Operating temperatures:
Blank = 0..85oC
9   Special conditions (n/a)

It's interesting to note that the PC2-5300 memory modules under review use quite standard Micron DDR2-533 memory chips, which are designed to operate in this mode with standard 4-4-4 timings. In particular, the same chips, but with lead plating, are used in DDR2 Kingmax modules.

SPD module chip data

Description of the SPD general standard:
JEDEC Standard No. 21-C, 4.1.2 - SERIAL PRESENCE DETECT STANDARD, General Standard

Description of the SPD specific standard for DDR2:
JEDEC Standard No. 21-C, 4.1.2.10 - Appendix X: Specific SPDs for DDR2 SDRAM (Revision 1.0)
JC-45 Appendix X: Specific PD's for DDR2 SDRAM (Revision 1.1)

Function Byte Value Expansion
Fundamental Memory Type 2 08h DDR2 SDRAM
Number of Row Addresses on this assembly 3 0Dh 13 (RA0-RA12)
Number of Column Addresses on this assembly 4 0Ah 10 (CA0-CA9)
Number of DIMM Banks 5 61h 2 physical banks
Data Width of this assembly 6 40h 64 bit
Voltage Interface Level of this assembly 8 05h SSTL 1.8V
SDRAM Cycle time (tCK) at maximum supported CAS# latency (CL X) 9 30h 3.00 ns (333.3 MHz)
DIMM configuration type 11 00h Non-ECC
Refresh Rate/Type 12 82h 7.8125 ms – 0.5x reduced self-refresh
Primary SDRAM Width (organization type) of the memory module chips 13 08h x8
Error Checking SDRAM Width (organization type) of the memory chips in the ECC module 14 00h Not defined
Burst Lengths Supported (BL) 16 0Ch BL = 4, 8
Number of Banks on SDRAM Device 17 04h 4
CAS Latency (CL) 18 10h CL = 4
Minimum clock cycle (tCK) at reduced CAS latency (CL X-1) 23 00h Not defined
Minimum clock cycle (tCK) at reduced CAS latency (CL X-2) 25 00h Not defined
Minimum Row Precharge Time (tRP) 27 3Ch 15.0 ns
45, CL = 4
Minimum Row Active to Row Active delay (tRRD) 28 1Eh 7.5 ns
2.5, CL = 4
Minimum RAS to CAS delay (tRCD) 29 3Ch 15.0 ns
5, CL = 4
Minimum Active to Precharge Time (tRAS) 30 2Dh 45.0 ns
15, CL = 4
Module Bank Density 31 40h 256 MB
Write recovery time (tWR) 36 3Ch 15.0 ns
5, CL = 4
Internal write to read command delay (tWTR) 37 1Eh 7.5 ns
2.5, CL = 4
Internal read to precharge command delay (tRTP) 38 1Eh 7.5 ns
2.5, CL = 4
Minimum Active to Active/Refresh Time (tRC) 41, 40 3Ch, 00h 60.0 ns
20, CL = 4
Minimum Refresh to Active/Refresh Command Period (tRFC) 42, 40 4Bh, 00h 75.0 ns
25, CL = 4
Maximum device cycle time (tCKmax) 43 80h 8.0 ns
SPD Revision 62 10h Revision 1.0
Checksum for Bytes 0-62 63 E0h 224 (true)
Manufacturer’s JEDEC ID Code (only the first significant bytes are shown) 64-71 FFh, 7Fh,
9Eh
Corsair
Module Part Number 73-90 - CM2X512-5400C4
Module Manufacturing Date 93-94 00h, 00h Not defined
Module Serial Number 95-98 00h, 00h,
00h, 00h
Not defined

According to the SPD chip data, this module can operate with the only possible CAS# latency (CL X) of 4, with the 3.00 ns cycle time, that is at 333.3 MHz (in DDR2-667 mode). Memory timings for this case can be written as 4-5-5-15, which actually conflicts with the data provided in the module specification. Nevertheless, absolute values of tRCD (15.0 ns), tRP (15.0 ns) and tRAS (45.0 ns) can be considered standard for DDR2-533 modules, familiar to us from the previous reviews (which is not at all surprising, considering the use of "standard" DDR2-533 chips). Among the other features of the SPD chip is the lack of data on the manufacturing date and the module serial number.

Testbed Configurations and Software

Mainboards based on the chipsets of Intel 915 series

Testbed #1

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i915G
  • Mainboard: Intel D915GUX, BIOS 1028 dated 06/29/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Testbed #2

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i915P
  • Mainboard: Foxconn 915A01-P-8EKRS, BIOS 6.00 PG dated 06/10/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Testbed #3

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i915G
  • Mainboard: Foxconn 915M03-G-8EKRS2, BIOS 6.00 PG dated 05/29/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Testbed #4

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i915P
  • Mainboard: MSI 915P Neo2, BIOS V1.3B0 dated 09/08/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Testbed #5

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i915G
  • Mainboard: MSI 915G Combo, BIOS 080011 dated 07/14/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Testbed #6

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i915G
  • Mainboard: ASUS P5GDC-V, BIOS 1003.003 dated 08/18/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Mainboards based on the chipsets of Intel 925 series

Testbed #7

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i925X
  • Mainboard: Gigabyte 8ANDXP-D, BIOS F1 dated 06/07/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Testbed #8

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i925X
  • Mainboard: Intel D925XCV, BIOS 1259 dated 08/19/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Testbed #9

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i925X
  • Mainboard: ASUS P5AD2, BIOS 1004.007 dated 07/02/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Testbed #10

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i925X
  • Mainboard: MSI 925X Neo, BIOS 6.00 PG dated 06/18/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Testbed #11

  • CPU: Intel Pentium 4 2.8 GHz (Prescott core, 1 MB L2)
  • Chipset: Intel i925X
  • Mainboard: Foxconn 925A01-8EKRS, BIOS 6.00 PG dated 08/28/2004
  • Memory: 2x512 MB Corsair DDR2-675
  • Video: Leadtek PX350 TDH, nVidia PCX5900
  • HDD: WD Raptor WD360, SATA, 10000 rpm, 36Gb
  • Operating system: Windows XP Professional Service Pack 2
  • Drivers: Intel Chipset Utility 6.0.1.1002, nVidia Forceware 61.77

Test Results

As we have already written before, we tested memory modules in two modes. The first series of tests (performance tests) were carried out in normal mode, that is with standard timings written in the SPD chip. The second series (stability tests) – in the "extreme" mode with maximum possible timings for a given module on a given mainboard.

Mainboards based on the chipsets of Intel 915 series

Performance tests

As the current generation of Intel 915/925 chipsets does not allow the memory subsystem to operate at the frequencies over 300 (and in most mainboards 266.7) MHz, the first series of tests – performance tests of DDR2 Corsair modules – was carried out at the 266.7 MHz memory frequency (in DDR2-533 mode) with the nominal (according to the DDR2 standard) 1.8 V voltage and with 4-4-4-12 timings, which were set by default in BIOS in all tested mainboards, although the DDR2-533 mode is not written in the SPD chips of the modules.



Parameter*
Testbed 1
Testbed 2
Testbed 3
Testbed 4
Testbed 5
Testbed 6
Timings
4-4-4-12
4-4-4-12
4-4-4-12
4-4-4-12
4-4-4-12
4-4-4-12
Average memory read bandwidth, MB/sec
4505
4504
4497
4567
4524
4530
Average memory write bandwidth, MB/sec
2086
2080
2083
2124
2071
2075
Max. memory read bandwidth, MB/sec
6390
6395
6396
6491
6416
6434
Max. memory write bandwidth, MB/sec
4267
4267
4267
4324
4267
4282
Minimum Pseudo-Random Access Latency, ns**
54.4
54.6
54.6
53.8
54.4
54.2
Maximum Pseudo-Random Access Latency, ns**
63.3
63.6
63.7
62.7
63.4
63.2
Minimum Random Access Latency, ns**
128.6
128.5
128.4
126.9
128.8
128.0
Maximum Random Access Latency, ns**
153.7
153.5
153.5
151.6
153.8
153.0

*the best results are in bold
**Block size – 16 MB

MSI 915P Neo2 (Testbed #4) is again leading among the mainboards based on the 915 series of Intel chipsets. It is followed by ASUS P5GDC-V (Testbed #6) and MSI 915G Combo (Testbed #5) pushing Foxconn (Testbeds #2, 3) and Intel (Testbed #1) mainboards to the last place. As in previous tests of Kingston and Kingmax modules, no advantage can be seen of the i915P chipset over i915G (or vice versa).

Stability tests

According to our test methods, the second series of tests – DDR2 Corsair stability tests – were carried out with minimum possible timings, which would not lead to glitches. In mainboards allowing memory voltage control from BIOS we set this voltage to 1.9 V recommended by the module manufacturers. Memory voltage in other mainboards was supposed to be nominal 1.8 V.

Note that Corsair modules also revealed the strange behavior, previously demonstrated in our tests by Kingmax modules. Namely, both memory types allow any tRAS values in the configuration registers of the chipset, from 15 to 3, without any reaction. In this connection, we again have to content ourselves with the first three timing parameters only.

Parameter*
Testbed 1
Testbed 2
Testbed 3
Testbed 4
Testbed 5
Testbed 6
Timings
4-4-3
(1.8 V)
4-3-3
(1.8 V)
4-3-3
(1.8 V)
3-3-3
(1.9 V)
3-3-3
(1.9 V)
3-3-3
(1.9 V)
Average memory read bandwidth, MB/sec
4526
4539
4543
4749
4676
4690
Average memory write bandwidth, MB/sec
2128
2174
2168
2251
2336
2295
Max. memory read bandwidth, MB/sec
6430
6448
6456
6552
6465
6487
Max. memory write bandwidth, MB/sec
4267
4266
4267
4324
4267
4282
Minimum Pseudo-Random Access Latency, ns**
54.3
54.3
54.3
52.0
52.8
52.6
Maximum Pseudo-Random Access Latency, ns**
63.3
63.2
63.2
60.3
61.4
61.0
Minimum Random Access Latency, ns**
125.8
122.3
122.4
117.5
119.3
118.9
Maximum Random Access Latency, ns**
151.4
147.9
148.1
142.5
144.4
144.0

*the best results are in bold
**Block size – 16 MB

The data in this table clearly demonstrates the direct relation between the voltage and the minimal CAS# latency. So, DDR2 Corsair modules operate steadily with tCL = 3 and 1.9 V. But when it's reduced to nominal (1.8 V), the minimal stable value of tCL = 4. Thus, maximum operating stability of the memory subsystem and the minimal timings – 3-3-3 – are demonstrated by MSI (Testbeds #4, 5) and ASUS (Testbed #6) mainboards. Since it's impossible to control memory voltage in Foxconn mainboards, they demonstrate worse results – minimum 4-3-3 timings. And at last, the worst results, both by stability (4-4-3 timings) and by performance in normal and extreme modes are demonstrated by Intel D915GUX.

Mainboards based on Intel 925X

Performance tests

Among the mainboards based on Intel 925X, the first series of tests again puts forward the product from MSI – MSI 925X Neo mainboard (Testbed #10). The second place, with minimal differences, is taken by Gigabyte 8ANDXP-D (Testbed #7) and ASUS P5AD2 (Testbed #9) mainboards. Foxconn 925A01 (Testbed #11) is almost on the par with them and by some parameters (maximum real memory bandwidth) it even outscores them. The worst results (noticeably lesser real memory bandwidth and noticeably larger memory latency) are demonstrated by Intel D925XCV (Testbed #8).

Parameter*
Testbed 7
Testbed 8
Testbed 9
Testbed 10
Testbed 11
Timings
4-4-4-12
4-4-4-12
4-4-4-12
4-4-4-12
4-4-4-12
Average memory read bandwidth, MB/sec
4682
4527
4669
4717
4653
Average memory write bandwidth, MB/sec
2464
2432
2456
2461
2425
Max. memory read bandwidth, MB/sec
6412
6363
6400
6515
6422
Max. memory write bandwidth, MB/sec
4287
4267
4282
4327
4267
Minimum Pseudo-Random Access Latency, ns**
51.8
54.4
51.9
51.3
52.1
Maximum Pseudo-Random Access Latency, ns**
60.0
63.1
60.1
59.5
60.5
Minimum Random Access Latency, ns**
123.4
128.2
123.4
122.4
124.0
Maximum Random Access Latency, ns**
148.1
153.2
148.2
146.9
149.0

*the best results are in bold
**Block size – 16 MB

In performance tests of DDR2 Corsair modules with mainboards based on Intel 925X the first place is again taken by the MSI product – 925X Neo mainboard (Testbed #10). The second place, almost with the same result, is shared by three mainboards – Gigabyte 8ANDXP-D (Testbed #7), ASUS P5AD2 (Testbed #9) and Foxconn 925A01 (Testbed #11). Corsair modules demonstrate the worst memory bandwidth and latency on the Intel D925XCV mainboard, as was the case with previously tested Kingston and Kingmax modules. As before, the memory performance on mainboards based on i925X is on the whole higher than that on the i915P/G mainboards.

Stability tests



Parameter*
Testbed 7
Testbed 8
Testbed 9
Testbed 10
Testbed 11
Timings
3-3-3
(1.9 V)
3-3-3
(1.95 V)
3-3-3
(1.9 V)
3-3-3
(1.9 V)
4-3-3
(1.9 V)
Average memory read bandwidth, MB/sec
4886
4688
4871
4912
4681
Average memory write bandwidth, MB/sec
2486
2455
2470
2447
2394
Max. memory read bandwidth, MB/sec
6487
6435
6469
6577
6473
Max. memory write bandwidth, MB/sec
4287
4267
4282
4327
4267
Minimum Pseudo-Random Access Latency, ns**
49.5
51.7
49.6
49.2
52.0
Maximum Pseudo-Random Access Latency, ns**
57.9
60.0
57.9
57.5
60.4
Minimum Random Access Latency, ns**
113.2
117.4
113.5
112.5
117.7
Maximum Random Access Latency, ns**
137.5
142.1
137.6
136.4
142.6

*the best results are in bold
**Block size – 16 MB

As you can see from the table data, all tested mainboards based on i925X allow increasing the memory voltage (to 1.9 or 1.95 V and higher). Thus, the modules under review operate steadily almost on all mainboards, when the CAS latency = 3, except for Foxconn 925A01 (Testbed #11), where Corsair modules operate steadily only when tCL = 4, though the voltage is 1.9 V. Due to the increased CAS latency, this mainboard demonstrates memory performance results comparable to those of Intel D925XCV (Testbed #8).

Results

Our tests demonstrate that DDR2 Corsair modules are stable to operate in DDR2-533 mode with really fantastic 3-3-3 timings on most mainboards, which support the 1.9V memory voltage recommended by the manufacturers. The best results, both in performance and in memory stability, are again demonstrated by MSI (925X Neo and 915P Neo2), ASUS (P5AD2 and P5GDC-V) and Gigabyte 8ANDXP-D mainboards; the worst – by the Intel mainboards (D925XCV and D915GUX).

Dmitry Besedin (dmitri_b@ixbt.com)

October 18, 2004


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