I have Crucial 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit in my system now model# CT2KIT25664AA80E I want to buy 4 more gig totaling 8G for my vista. This is what I'm looking at Crucial 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit model#CT2KIT25664AA800 nobody's around at crucial and if I get it asap it's cheap but the model #'s are diff so I wonder if I buy this if it will be compatible with my existing RAM ? thnx AMD 64x2 4000+ ASUS M2N-E Mobo w/ ultra nforce 570 Arctic Cooling 64 Freezer Pro HS/F w/as5 4GIG of Crucial DDR2 800 6400 2gig x 2 2 SATAII WD 80gig Hard drives 8Mb cache Antec 550w

Modules compatible with Asus M2N-E http://www.crucial.com/store/listpa... Click on: See all compatible parts Then click on Show all in the list CT2KIT25664AA80E is NOT listed. CT2KIT25664AA800 IS listed http://www.crucial.com/store/mparts... 4GB kit (2GBx2), 240-pin DIMM, DDR2 PC2-6400 memory module CT2KIT25664AA800 Module Size: 4GB kit (2GBx2) Package: 240-pin DIMM Feature: DDR2 PC2-6400 Specs: DDR2 PC2-6400 • CL=6 • Unbuffered • NON-ECC • DDR2-800 • 1.8V • 256Meg x 64 • ...... CT2KIT25664AA80E found on the web: http://www.cdw.ca/shop/products/def... RAM Capacity of Module in Kit: 2 GB CAS Latency: CL5 Data Integrity Check: Non-ECC Form Factor: DIMM 240-pin Lead Plating: Gold Memory Specification Compliance: PC2-6400 Memory Speed: 800 MHz Module Configuration: 256 x 64 Module Height (inch): 1.18 Modules in Kit: 2 Registered or Buffered: Unbuffered Storage Capacity: 4 GB Supply Voltage: 1.8 V Technology: DDR2 SDRAM ..... In the case of AM2 mboards, the memory controller is built into the cpu, and that's what the ram must be compatible with. Despite the fact CT2KIT25664AA80E is not listed for your mboard model, if it's working fine now, it SHOULD work fine along with the CT2KIT25664AA800. The only obvious difference appears to be CT2KIT25664AA80E is rated at CL=5, CT2KIT25664AA800 is rated at CL=6, and CT2KIT25664AA80E is usually more expensive than CT2KIT25664AA800. If you install both sets of modules, all the ram will run at CL=6. Would you be able to perceive the difference between CL=6 and CL=5?? Not likely. The CL rating only applies when the ram is first accessed - when it continues to be accessed, which it is the vast majority of the time, CL 5 ram runs at the same speed as CL 6 ram, if other ram specs are equal. The amount of ram, if you actually benefit from having more, is a lot more important than the CL rating, and a lot more important than whether it is running in dual channel mode or not. But do you actually need more ram? Probably NOT! You will not notice ANY difference with more ram unless you actually have programs that will run better with more ram. Ultimate Memory Guide How Much Memory Do You Need? etc. http://www.kingston.com/tools/umg/u... After a certain minimal amount, more ram will NOT make your speed on the internet faster - that depends on the max speed of internet package you're paying for, which is much slower than the speed at which your cpmuter runs otherwise, and that's the bottleneck, not the amount of ram you have installed. Upgrading your cpu to a faster model will make a lot more of a noticable difference than adding more ram will.

As Tubes pointed out, the RAM you currently have is DDR2-800, CL5, 1.8v, 256 x 64. Those are the specs you need to match up for compatibility. The kit you mentioned, CT2KIT25664AA800, is CL6 so it's slower RAM. It may or may not be a compatibility issue but it will force ALL 4 sticks to run at CL6. You *may* be able to manually configure the RAM to run as CL5, but there's no guarantee. I tried entering your original RAM's model number at crucial.com & got this: "Sorry, your search for "CT2KIT25664AA80E" returned no results, please try a new search or try one of the tools below." What do you use your system for that would require 8GB RAM?

vista x64 with the glass engine & built in overhead running simultaneously with web development tools, dvd ripping/ burning and graphics tools 4 HDs and plan for more on usb. I run alot of this stuff at the same time, and, hey finally 64 bit. This mobo only takes a max of 8G. The sticks are really cheap so I figured why not, but I may wait until I can talk to a crucial rep.

Better jump on this deal while you can: http://shop2.frys.com/product/5530560

Thanx for the detailed response Tubes. and Thanx for the deal post Jam.

Well, I got the 4 more gigs. I just could not get over how much ram vista x64 ate at start-up,(830mb as opposed to 180 in xp pro) even after I tinkered with the services but since I don't want to turn off services like I did in XP Pro so I got the ram. It'll be here tomorrow.