Can I Go DDR2 667 to DDR2800 in myDv6000t

I have a DV6000t Vista with 2GB ram. I'm looking to go to Win7 and to 4GB RAM. My RAM is DDR2 667. Can I use DDR2 800?

 

You can add DDR2 800 modules, but your chipset and processor might not support the DDR2 800 mode, so the RAM modules you add will automatically downclock back to 667.

 

Would you say this is a given or is there a way I can look into it? The price is the same so maybe just go for it?

 

Well the common way to figure out the max RAM clock on your laptop with an Intel chip is to see what is the max CPU Bus Speed your CPU is going. Apparently, your T7200 can only hit 667 max on the Bus Speed on stock. So, the RAM can only go as far as 667 to match with your CPU.

As for the RAM selection, DDR 2 800 usually has higher CAS latency times than a 667. Since you are stuck with 667, go for the RAM that has lower CAS latency times and usually the 667 will trump over the 800 in that regard and since your laptop can't even support 800 in the current setup, 800 emulating 667 speeds with higher CAS latency is not as good as native 667 with lower CAS latency.

 

Interesting info. Thanks

 

This isn't always the case; a lot depends on the actual memory controller in your chipset. For something running the older T7200, though, it's probably true, especially given that it seems to have come with 667 in the first place.

Except that as RAM changes speeds, so does it's CAS latency. For example, the PC2-6400 I have in my notebook has CAS latency of 6 when running at 400(800), 5 at 333(667), and 4 at 266(533). This means that even though it has a higher latency at 800, when it downclocks, the latency is often comparable. Even so, I doubt it'll be relevant/noticeable even if the CAS latency was slightly higher, unless you're specifically looking for it.

 

That is true, but if your CPU is 667 but your controller is 800, doesn't the RAM still operate at the max Bus Speed of the CPU regardless?

That I didn't know, but either way in his case, this is negligible.

 

Depends on how it's structured. As given in this article on Wikipedia, there are systems available where the memory ratio is not 1:1, but is instead 4:5 or some other ratio (under the Memory section). This would mean that the RAM would be operating at a different speed than the CPU, due to the different ratio.

That was more to point out that he would be perfectly fine using the DDR2 800 RAM instead of the DDR2 667 RAM. So even if the DDR2 800 RAM might be listed as having higher latencies than the DDR2 667 RAM, there's an excellent chance that when the DDR2 800 RAM clocks down to DDR2 667 speed, the latency would be comparable. Basically, he should go for whichever is cheaper and more easily available, given that both should run adequately in his system (unless he overclocks, but that's an entirely different kettle of fish).