Question about notebook cpu/mb bus speed vs. RAM speed........

[herbiehancock]

OK.....bought the HP dv6103nr notebook at BB on Black Friday. I want to upgrade the RAM but am a bit confused here.

The cpu is an Intel Core Solo, T1350, 1.86GHz with a 533MHz frontside bus speed.

The RAM currently installed is DDR2 RAM....specifically PC2-5300, which is 667MHz speed.

So, can the replacement RAM actually be PC2-4200, which is described as running at 533MHz, or do I really need to put PC2-5300 into it? There is a substantial price difference between the two speeds of RAM.

Or, why is HP putting PC2-5300 DDR2 RAM in a notebook that has an FSB speed of 533MHz.....is there something I am missing?

TIA!!!

 

[stevty2889]

You could be PC2-4200 in, but it won't be guranteed to work in dual channel with your current stick of RAM. Both sticks will be then running at 533mhz, with the timings of the slowest stick. 667mhz ram is probably just more common now. Even 533mhz ram is running at higher than FSB speed(533mhz FSB is 133x4, 533mhz ram is 266x2).

 

[herbiehancock]

Well, did some researching and finally answered my own question.....which I should have done in the first place.....DUH!!

In the case of the HP laptop, while the cpu does indeed run at a bus speed of 533MHz, the onboard graphics chip on the Intel 945GM chipset (the motherboard's chipset in the HP), which is the Graphics Media Accelerator 950, was designed around having DDR2 667MHz memory bandwidth for best operation.

"Up to 10.6 GB/sec memory bandwidth with DDR2 667 system memory"

It took some digging on Intel's web site to finally get the answer, but that's it. The cpu isn't the reason the RAM is rated at a faster speed than the FSB, it's the fact that the graphics accelerator needs the extra bandwidth to work its best. As the 945GM motherboard chipset was designed for cpu's with a FSB of 667, it only makes sense that the rest of the integrated components were initially designed to work with that memory bandwidth, too.

Also found out the 533MHz Core Solo cpu's were an addition to the Core lineup of mobile cpu's.....the first released were all 667 FSB chips. The initial release of Core Solos were the T1300 and T1400, both 667MHz parts. Then Intel released three additional Solos.....two Ultra Low Voltage Solos, the U1300 and U1400, along with the T1350 part....all 533MHz FSB chips.

This sequence was followed in the Core Duo lineup at the same time.....original release was all 667MHz parts, followed by two ULV chips, both 533 parts, and two non-ULV parts, the U2400, U2500 (both ULV's) and the T2050 and the T2250, again all 533MHz FSB cpu's.

Seems these non-ULV slower FSB chips were more a value rendition of their faster brothers.

So, now we all know!!