RAM question - 4gb not bought as a 'kit'

I'm running Windows 7 64 bit on my new semi-homebuilt PC. I replaced
the RAM that came with my bundle, a 1 GB generic stick, with 2GB of
Buffalo Select, 800mhz, and then bought another about ten days later.
I didn't know that it's desirable to buy as a kit then. Can I expect
problems, or is it merely that buying a kit is ideal? To be fair, the
machine is running great, after a fortnight of instability when a 3
editions outdated BIOS was still installed and I think a wrong setting
for the RAM's bus speed in the BIOS.

This is what I get, that's relevant, from CPU-Z. Does this look
okay? I see the CAS latencies etc are different for both sticks,
unless the readings I get for my laptop, which is all stock parts.

Would 200mhz bus speed, if that is what the BIOS setting was for, be
right for PC6400 RAM? I think the auto setting I had before was
400mhz, and certainly it was not stable then. The Windows Experience
Index for what it's worth is 7.1. The motherboard is an Asus M2N68
SE2, the CPU an AMD X2 Regor Core 3 ghz. (Why does one of the lines
read PC6400 (400mhz)? It's confusing that 800mhz RAM has these two
other speeds...)
Many thanks in advance.

Chipset
-------------------------------------------------------------------------

Northbridge NVIDIA GeForce 7025 rev. A3
Southbridge NVIDIA nForce 630a rev. A2
Graphic Interface PCI-Express
PCI-E Link Width x16
PCI-E Max Link Width x16
Memory Type DDR2
Memory Size 4096 MBytes
Channels Dual, (Unganged)
Memory Frequency 200.9 MHz (1:1)
CAS# latency (CL) 5.0
RAS# to CAS# delay (tRCD) 3
RAS# Precharge (tRP) 3
Cycle Time (tRAS) 9
Bank Cycle Time (tRC) 12
Command Rate (CR) 2T
Uncore Frequency 1607.4 MHz

Memory SPD
-------------------------------------------------------------------------

DIMM # 1
SMBus address 0x50
Memory type DDR2
Module format Regular UDIMM
Manufacturer (ID) Melco (7F7F7F8300000000)
Size 2048 MBytes
Max bandwidth PC2-6400 (400 MHz)
Part number
Number of banks 2
Data width 64 bits
Correction None
Nominal Voltage 1.80 Volts
EPP no
XMP no
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 4.0-4-4-12-16 @ 266 MHz
JEDEC #2 5.0-5-5-18-23 @ 400 MHz
JEDEC #3 6.0-5-5-18-23 @ 400 MHz

DIMM # 2
SMBus address 0x51
Memory type DDR2
Module format Regular UDIMM
Manufacturer (ID) Melco (7F7F7F8300000000)
Size 2048 MBytes
Max bandwidth PC2-6400 (400 MHz)
Part number
Number of banks 2
Data width 64 bits
Correction None
Nominal Voltage 1.80 Volts
EPP no
XMP no
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 3.0-3-3-9-12 @ 200 MHz
JEDEC #2 4.0-4-4-12-16 @ 266 MHz
JEDEC #3 5.0-5-5-18-23 @ 400 MHz

Using a kit is preferred since the two dims are manufactured at the the same
time on the same production line using the same production process.
This does not mean that two dims with the same specs from the same vendor
using the same production process will not work without a problem if
purchased at different times.

"poachedeggs" <poachedeggs@hotmail.co.uk> wrote in message
news:e662feda-9c58-4d31-9f2f-b7a6227c0150@t41g2000yqt.googlegroups.com...
> I'm running Windows 7 64 bit on my new semi-homebuilt PC. I replaced
> the RAM that came with my bundle, a 1 GB generic stick, with 2GB of
> Buffalo Select, 800mhz, and then bought another about ten days later.
> I didn't know that it's desirable to buy as a kit then. Can I expect
> problems, or is it merely that buying a kit is ideal? To be fair, the
> machine is running great, after a fortnight of instability when a 3
> editions outdated BIOS was still installed and I think a wrong setting
> for the RAM's bus speed in the BIOS.
>
> This is what I get, that's relevant, from CPU-Z. Does this look
> okay? I see the CAS latencies etc are different for both sticks,
> unless the readings I get for my laptop, which is all stock parts.
>
> Would 200mhz bus speed, if that is what the BIOS setting was for, be
> right for PC6400 RAM? I think the auto setting I had before was
> 400mhz, and certainly it was not stable then. The Windows Experience
> Index for what it's worth is 7.1. The motherboard is an Asus M2N68
> SE2, the CPU an AMD X2 Regor Core 3 ghz. (Why does one of the lines
> read PC6400 (400mhz)? It's confusing that 800mhz RAM has these two
> other speeds...)
> Many thanks in advance.
>
> Chipset
> -------------------------------------------------------------------------
>
> Northbridge NVIDIA GeForce 7025 rev. A3
> Southbridge NVIDIA nForce 630a rev. A2
> Graphic Interface PCI-Express
> PCI-E Link Width x16
> PCI-E Max Link Width x16
> Memory Type DDR2
> Memory Size 4096 MBytes
> Channels Dual, (Unganged)
> Memory Frequency 200.9 MHz (1:1)
> CAS# latency (CL) 5.0
> RAS# to CAS# delay (tRCD) 3
> RAS# Precharge (tRP) 3
> Cycle Time (tRAS) 9
> Bank Cycle Time (tRC) 12
> Command Rate (CR) 2T
> Uncore Frequency 1607.4 MHz
>
> Memory SPD
> -------------------------------------------------------------------------
>
> DIMM # 1
> SMBus address 0x50
> Memory type DDR2
> Module format Regular UDIMM
> Manufacturer (ID) Melco (7F7F7F8300000000)
> Size 2048 MBytes
> Max bandwidth PC2-6400 (400 MHz)
> Part number
> Number of banks 2
> Data width 64 bits
> Correction None
> Nominal Voltage 1.80 Volts
> EPP no
> XMP no
> JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
> JEDEC #1 4.0-4-4-12-16 @ 266 MHz
> JEDEC #2 5.0-5-5-18-23 @ 400 MHz
> JEDEC #3 6.0-5-5-18-23 @ 400 MHz
>
> DIMM # 2
> SMBus address 0x51
> Memory type DDR2
> Module format Regular UDIMM
> Manufacturer (ID) Melco (7F7F7F8300000000)
> Size 2048 MBytes
> Max bandwidth PC2-6400 (400 MHz)
> Part number
> Number of banks 2
> Data width 64 bits
> Correction None
> Nominal Voltage 1.80 Volts
> EPP no
> XMP no
> JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
> JEDEC #1 3.0-3-3-9-12 @ 200 MHz
> JEDEC #2 4.0-4-4-12-16 @ 266 MHz
> JEDEC #3 5.0-5-5-18-23 @ 400 MHz