Mixing DDR3 memory and speed

[rjnkanwal]

Hi I have Dell Studio XPS 435MT with i7920 processor. I had 1gbx6 1066mhz factory installed dimms earlier. I just upgraded memory to 12gb with crucial ballistix tacticle 4gbx3 1600mhz. Memory is recognised in bios as 1333mhz and there is no xmp to change anything being dell bios. CPU-Z is showing maximum bandwidth 667mhz which is 1333mhz. but I believe it is running at 1066 as CPU-Z is showing 531.9mhz under memory frequency.
Now the question is, if current memory is running at 1066mhz, can I put the three 1gb 1066 dimms in to make it 15gb or my current memory is actually running at 1333mhz and I am reading it wrong. Here is the log from CPU-Z.

Northbridge Intel X58 rev. 12
Southbridge Intel 82801JR (ICH10R) rev. 00
Graphic Interface PCI-Express
PCI-E Link Width x16
PCI-E Max Link Width x16
Memory Type DDR3
Memory Size 12 GBytes
Channels Triple
Memory Frequency 531.9 MHz (2:8)
CAS# latency (CL) 8.0
RAS# to CAS# delay (tRCD) 8
RAS# Precharge (tRP) 8
Cycle Time (tRAS) 19
Row Refresh Cycle Time (tRFC) 86
Command Rate (CR) 1T
Uncore Frequency 2127.7 MHz

Memory SPD
DIMM # 1
SMBus address 0x50
Memory type DDR3
Module format UDIMM
Manufacturer (ID) Crucial Technology (7F7F7F7F7F9B00000000)
Size 4096 MBytes
Max bandwidth PC3-10700H (667 MHz)
Part number BLT4G3D1608DT1TX0.
Serial number A31E3D11
Number of banks 8
Nominal Voltage 1.50 Volts
EPP no
XMP yes
XMP revision 1.3
AMP no
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 6.0-6-6-16-22 @ 444 MHz
JEDEC #2 8.0-8-8-22-30 @ 592 MHz
JEDEC #3 9.0-9-9-24-33 @ 666 MHz
XMP profile XMP-1600
Specification PC3-12800
Voltage level 1.500 Volts
Min Cycle time 1.250 ns (800 MHz)
Max CL 8.0
Min tRP 10.00 ns
Min tRCD 10.00 ns
Min tWR 15.00 ns
Min tRAS 30.00 ns
Min tRC 45.00 ns
Min tRFC 160.00 ns
Min tRTP 7.50 ns
Min tRRD 6.00 ns
Command Rate 2T
XMP timings table CL-tRCD-tRP-tRAS-tRC-CR @ frequency (voltage)
XMP #1 6.0-6-6-18-27-2T @ 600 MHz (1.500 Volts)
XMP #2 7.0-7-7-21-32-2T @ 700 MHz (1.500 Volts)
XMP #3 8.0-8-8-24-36-2T @ 800 MHz (1.500 Volts)

DIMM # 2
SMBus address 0x52
Memory type DDR3
Module format UDIMM
Manufacturer (ID) Crucial Technology (7F7F7F7F7F9B00000000)
Size 4096 MBytes
Max bandwidth PC3-10700H (667 MHz)
Part number BLT4G3D1608DT1TX0.
Serial number A31E3D10
Number of banks 8
Nominal Voltage 1.50 Volts
EPP no
XMP yes
XMP revision 1.3
AMP no
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 6.0-6-6-16-22 @ 444 MHz
JEDEC #2 8.0-8-8-22-30 @ 592 MHz
JEDEC #3 9.0-9-9-24-33 @ 666 MHz
XMP profile XMP-1600
Specification PC3-12800
Voltage level 1.500 Volts
Min Cycle time 1.250 ns (800 MHz)
Max CL 8.0
Min tRP 10.00 ns
Min tRCD 10.00 ns
Min tWR 15.00 ns
Min tRAS 30.00 ns
Min tRC 45.00 ns
Min tRFC 160.00 ns
Min tRTP 7.50 ns
Min tRRD 6.00 ns
Command Rate 2T
XMP timings table CL-tRCD-tRP-tRAS-tRC-CR @ frequency (voltage)
XMP #1 6.0-6-6-18-27-2T @ 600 MHz (1.500 Volts)
XMP #2 7.0-7-7-21-32-2T @ 700 MHz (1.500 Volts)
XMP #3 8.0-8-8-24-36-2T @ 800 MHz (1.500 Volts)

DIMM # 3
SMBus address 0x54
Memory type DDR3
Module format UDIMM
Manufacturer (ID) Crucial Technology (7F7F7F7F7F9B00000000)
Size 4096 MBytes
Max bandwidth PC3-10700H (667 MHz)
Part number BLT4G3D1608DT1TX0.
Serial number A31E3D1C
Number of banks 8
Nominal Voltage 1.50 Volts
EPP no
XMP yes
XMP revision 1.3
AMP no
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 6.0-6-6-16-22 @ 444 MHz
JEDEC #2 8.0-8-8-22-30 @ 592 MHz
JEDEC #3 9.0-9-9-24-33 @ 666 MHz
XMP profile XMP-1600
Specification PC3-12800
Voltage level 1.500 Volts
Min Cycle time 1.250 ns (800 MHz)
Max CL 8.0
Min tRP 10.00 ns
Min tRCD 10.00 ns
Min tWR 15.00 ns
Min tRAS 30.00 ns
Min tRC 45.00 ns
Min tRFC 160.00 ns
Min tRTP 7.50 ns
Min tRRD 6.00 ns
Command Rate 2T
XMP timings table CL-tRCD-tRP-tRAS-tRC-CR @ frequency (voltage)
XMP #1 6.0-6-6-18-27-2T @ 600 MHz (1.500 Volts)
XMP #2 7.0-7-7-21-32-2T @ 700 MHz (1.500 Volts)
XMP #3 8.0-8-8-24-36-2T @ 800 MHz (1.500 Volts)

The cas timings on the okd 1gb dimms are 7-7-7-20

Thanks
Raj

 

[Tradesman1]

You are running at 1066, and can try adding, but if they do play nice (no guarantees) they might drop to 800 or they may continue to run at 1066. And sorry but with the locked BIOS you can't make adjustments to get to 1333 - you could check for a BIOS update that may help.

 

[rjnkanwal]

You are running at 1066, and can try adding, but if they do play nice (no guarantees) they might drop to 800 or they may continue to run at 1066. And sorry but with the locked BIOS you can't make adjustments to get to 1333 - you could check for a BIOS update that may help.

Thanks Tradesman to confirm that it is running at 1066. I will try the 1gb dimms now and see what happens. There are two concerns in my mind
1. cas timings are different
2. I have six banks in triple channel. If I count the banks from right to left having cpu on the left then I am using Banks(white colour coded) 1, 3 and 5 for 4gb dimms. should I put the 1gb dimms in banks 2, 4 and 6(black colour coded) or they should be in different order.
Thanks
Raj

 

[Tradesman1]

Yes that's a good config, let us know what they do 😉

 

[rjnkanwal]

Hi Tradesman1
That configuration did work. Memory was running at 1066 with 15gb in total. I just felt although it could be my misconception that computer had slowed down. Pass mark test comparison showed slight difference. In some tests it was better and in some slightly poor, but latency had increased by 15% from 28 to 33.
So I took out the old 1gb modules, leaving just 12gb crucial and latency improved. I think that is more than enough for this computer. Even 6gb was good for me but now my son wanted to play Star Wars battlefront, so I upgraded the memory and also put in gigabyte gtx 960 4gb. That should be enough for the time.
Thanks for the help.
Raj