Inspiron E1505 Memory upgrade

I am sure this question must have been discussed previously, but here it is again: I own an E1505 with 2 x 512 MB (553Mhz) DIMM. Is it possible to buy 2 x 1GB Kingston 667Mhz DIMM and replace the original? Notice the bus speed difference.

If anyone of you has tried this out, can you please let me know the approximate improvement in performance? (tell me about Vista?)

 

You could, but it would still work at the maximum speed of 557Mhz because that is the maximum frequency your motherboard supports. There's no work-around that.

 

are you sure the motherboard supports 553Mhz at the maximum? very strange..because the processor is Core 2 Duo which is capable of performing at 800Mhz bus speed. Why provide a board that downgrades the performance by posing a bottleneck?

 

Since E1505 has 945GM chipset and support dual-channel memory, dual-channel DDR2-400 (2x400=800) is sufficient to be in sync with 800 FSB (quad pumped, 4X200=800). So, DDR2-533 and DDR2-667 are faster than 800 FSB in dual-channel configuration. CPU will only be able to access memory at DDR2-400 speed at 800 FSB even when DDR2 RAM is running at 533 or 667 MHz. But faster RAM will decrease the latency.

 

What? I think just wrong or missing the point, faster RAM will decrease latency? Goes back to bad writing or just wrong. 533Mhz has lower latency than 667Mhz & 800Mhz in most cases. I think DDR(2) and Dual Channel is throwing you for a big loop. DDR2 400 is not 2X400=800 it is 2X200=400 it is called PC3200, DDR2 533 is not 2X533 it is 2X266=533. DDR2 800 is 2X400=800Mhz called PC6400. Also even with FSB of 800Mhz memory bus only has 667Mhz on notebooks Intel.

To OP your system will run PC5300/5400 just fine. Use CPU-Z to find out you FSB if 667 your PC5300/5400 will run at 667Mhz if FSB is 533Mhz then PC5300/5400 will down clock to 533Mhz. Dell sells 667Mhz RAM when you order after purchase even if your system can only run it at 533Mhz. So yes you can and it may even run faster depends on FSB.

 

okay, let me explain.

Suppose two DDR2 memory both running at cl=5 but at different frequencies of 533Mhz and 667Mhz. Latency seems to be the same for both in terms of cycles since both of them has latency cycle (CL) as 5. But each cycle at 667 MHz is shorter compared to 533 MHz. So, DDR2-667 has lower latency in terms of time (not cycles).

2x in "2x400" is due to dual-channel. Memory is not running at 800 but it can effectively be in sync with 800 FSB due to double bandwidth in dual channel mode. On Intel platform, to saturate the memory bandwidth of 800 FSB, dual channel DDR2-400 is sufficient, hence 2x400.

Similarly;
FSB 800 -> DDR2-400 dual channel
FSB 1066 -> DDR2-533 dual channel
FSB 1333 -> DDR2-667 dual channel

So, DDR2-533 and DDR2-667 in dual channel mode are faster than required for FSB=800 MHz.