T40 BIOS and CPU upgrade, RAM latency

[cuzman]

Had the dreaded GPU problem on the motherboard which couldn't be fixed by a reflow, so a new motherboard is on the way.

It had a 1.3GHz Banias and I feel the need for an upgrade whilst I'm replacing the motherboard. The queries are:

1) Will any standard voltage Banias or Dothan run on the earliest BIOS on the T40? I'm not sure which BIOS the replacement motherboard will have.

http://processorfinder.intel.com/List.aspx?ProcFam=942

2) Will the heatsink I have be able to cool any of these, or from whereon do I need a better one?

3) Lastly, a potential RAM upgrade, to say 2x 512MB, could also be on the cards. I'm pretty sure the standard stuff was 256MB PC2100 CL2.5 (?). Does the BIOS facilitate the Bus ratio to 3:4 to run the 100MHz external PU clock at 133MHz?

Crucial's website recommends PC2700. Is there any point in going to PC2700 when the CPU only has an external clock of 100MHz? Can I run the RAM 3:5 at 166MHz?

[lithium726]

No. You need a BIOS from at least when the T42 was released for the Dothan, the system needs a microcode update.

The fan will be fine for any chip.

A T40 board will run the memory at 266mhz (133x2), a T41/T42 will run it at 333 (166x2). There is no way around this, the T40 uses an older stepping of the i855pm. PC2700 (333) will run just fine, the system will just clock it to 266 instead.

[sjthinkpader]

CL is CAS Latency. CAS is Column Address Strobe. CL is the number of clock cycles it takes after the RAM chip got column addresses (data location) from the North Bridge for the RAM to send out data requested.

In terms of CAS Access Time, there were very little improvements made in the past 10 years. As the clock cycles got shorter, the CAS Latency actually got longer. So the CAS Access Time (tCAC) had been at around 7.5nSec for a long time, even for the current DDR2 generation.

lithium is correct, MB controls the speed and not the RAM. RAM is rated at max speed. They may work slower but usually not faster.