DDR2-533 -> DDR2-800 Laptop RAM Upgrade Questions

I have recently been shopping around for some RAM to upgrade my 1GB DDR2-533 laptop RAM memory to 2GB. I was, however, unable to find fair priced DDR2-533 memory modules. I instead bought a 2GB module of Transcend DDR2-800 RAM (which is cheaper than the available 1GB DDR2-533 and has the same price with an equally sized DDR2-667).

I've gathered my details from the software, CPU-Z (details below) and have some questions about the upgrade:

I would like to know if would it be OK to install the old RAM with the new one as it appears my new DDR2-800 RAM module is running in DDR2-533 speeds?

Can I enable my new RAM to run at DDR2-800 speeds? Note: I can't find anything to configure the RAM timing/speed in the BIOS. I am also running the latest BIOS version available from the ASUS website.

Will it make a difference if I bought a DDR2-667 RAM instead (like in speed or compatibility with the old RAM module)?

Other details: The new RAM is running by itself with one extra slot free. My laptop is an ASUS A6R, Intel Celeron M. 2 memory module slots. 128MB shared memory for the ATI Xpress 200M graphics card. The OS is Windows XP SP3.


CPU-Z Info:

Old RAM:

DIMM # 1
SMBus address 0x50
Memory type DDR2
Module format SO-DIMM
Manufacturer (ID) Kingston (7F98000000000000)
Size 1024 MBytes
Max bandwidth PC2-4300 (266 MHz)
Part number 9905295-031.B00LF
Serial number
Manufacturing date Week 20/Year 07n
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 5.0-4-4-12-16 @ 266 MHz

Chipset Settings:

Channels Single
Memory Frequency 266.5 MHz ()
CAS# latency (CL) 4.0
RAS# to CAS# delay (tRCD) 4
RAS# Precharge (tRP) 4
Cycle Time (tRAS) 12

New RAM:

DIMM # 1
SMBus address 0x50
Memory type DDR2
Module format SO-DIMM
Manufacturer (ID) Transcend Information (7F4F000000000000)
Size 2048 MBytes
Max bandwidth PC2-6400 (400 MHz)
Part number JM800QSU-2G
Serial number
Manufacturing date Week 11/Year 09n
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 5.0-5-5-15-20 @ 333 MHz
JEDEC #3 6.0-6-6-18-24 @ 400 MHz

Chipset Settings:

Channels Single
Memory Frequency 266.5 MHz ()
CAS# latency (CL) 4.0
RAS# to CAS# delay (tRCD) 4
RAS# Precharge (tRP) 4
Cycle Time (tRAS) 12

Hey dazed_00, As far as I know, technically speaking using old RAM with new RAM is okay. But I wouldn't advise it. As a rule of thumb you should run two 'matched' modules. By matched I mean they are the same make, same size, same speed, same everything. Running a unmatched pair can be unstable and in normal systems would bring the clock speed of your new RAM down. But considering that your new RAM is already running at the old speed, it wouldn't make much difference. As for running it at 800 MHz, it's not possible unless you can find the settings in your BIOS. I suspect that 533 MHz is the maximum bus speed of your laptop motherboard. That means buying the 667 MHz RAM won't make a difference. If you want to make doubly sure that your laptop can't run quicker RAM, look at your manual. The manufacturer will normally advise you on what RAM you can buy and what the max bus speed of the motherboard is. If you want a more noticeable difference in performance though, I suggest you buy a second 2GB RAM module, of the same type, and put that in the second slot. Depending on your OS, you should see between 3 and 4 GB of RAM. (This is especially dependant on whether your OS is 32-bit or 64-bit). But honestly, I don't think you'll see much of a performance increase if all you're doing is browsing the net. It would only be worth installing a second module if you're using RAM intensive applications, such as audio/visual production or photo editing. I hope that helps. Cheers Nahumi