compaq presario V3438TU RAM upgrade trouble

[abbabb]

my laptop Compaq Presario V3438TU has original RAM module Hynyx DDR2 PC2 - 5300 bus 667 MHz 512 MB.

I wanted to add a new memory Kingston DDR2 PC2 - 5300 bus 667 MHz 1GB, however, when I plugged that new one to the remaining slot (that laptop has 2 memory slots), the system could not boot up, just showed a blank screen.

 

I first thought that there was the incompatible between the old and new module, however, the system can only boot when 1 memory module (either 512M or 1G) was plugged on the original memory slot (in this case, the upper one). The presence of RAM module in the lower slot cause problem.

 

The same effect happened when I plugged the 512M module to another latop HP Cpmpaq 6520s (had original RAM Qimonda DDR2 PC2 - 5300 MHz 1GB): only 1 RAM module could make the system boot up, except that at this time, the memory must be in the lower slot

 

So I thought that I must change the something to make the system recognize the module in the non-original slot in both laptops (some jumper, maybe). However, I haven't found yet

 

Any one can help?, your supports are highly welcomed:)

 

Thanks

[ken_cinder]

They have to be installed in matching pairs in this case. 2x512 or 2x1GB.

 

The fact they work in 1 slot, is because that slot is DIMM0 in non dual channel configuration. 2 DIMMs requires what I just mentioned.

[abbabb]

They have to be installed in matching pairs in this case. 2x512 or 2x1GB.

 

The fact they work in 1 slot, is because that slot is DIMM0 in non dual channel configuration. 2 DIMMs requires what I just mentioned.

 

There is no configuration for Dual channel mode in both BIOSs of my 2 laptops. Moreover, it is said that when the 2 RAMs are not a matching pair, the system will automatically switch no non dual channel mode, is it correct?

 

DIMM0 you mentioned above seem correct because the Hp6520s has RAM inserted reversely compared with the Compaq one: in Compaq, the notch is on the right side, in HP, the notch is on the left side, that explained why in Compaq, I had to insert RAM in the upper slot while in Hp, I had to insert in the lower slot (1 in 2 laptop, I had to insert RAM upside down)

 

So do you think that the 2 RAMs must be a matching pair, no way to use the 512 M one with 1G one?

[ken_cinder]

Dual channel is automatic, there is no bios setting for it on ANY system.

 

The system can not run 2 independant channels for the DIMMS, they must be of the same type (PC xxxx) and size (512MB or 1GB, or what have you).

 

Only if special consideration and settings are made is anything otherwise possible, and this is not standard behaiour, especially on a retail end user system.

[abbabb]

Dual channel is automatic, there is no bios setting for it on ANY system.

 

The system can not run 2 independant channels for the DIMMS, they must be of the same type (PC xxxx) and size (512MB or 1GB, or what have you).

 

Only if special consideration and settings are made is anything otherwise possible, and this is not standard behaiour, especially on a retail end user system.

 

One good thing, this morning, I installed the Kingston 1G to my HP and the 2 1G RAMs (Kingston and Quimonda) ran well in dual chanel mode. However, the Presario could not run with the same 2 RAMs

 

So there may be a problem with 1 RAM slot in the Presario (the lower one)

[abbabb]

Dual channel is automatic, there is no bios setting for it on ANY system.

 

The system can not run 2 independant channels for the DIMMS, they must be of the same type (PC xxxx) and size (512MB or 1GB, or what have you).

 

Only if special consideration and settings are made is anything otherwise possible, and this is not standard behaiour, especially on a retail end user system.

 

Yesterday, I discovered that my friend laptop - a BENQ brand - has 1x1G + 1x2G RAM modules. Therefore, your saying that the system cannot run 2 different RAM modules seems not correct.

[ken_cinder]

Dual channel is automatic, there is no bios setting for it on ANY system.

 

The system can not run 2 independant channels for the DIMMS, they must be of the same type (PC xxxx) and size (512MB or 1GB, or what have you).

 

Only if special consideration and settings are made is anything otherwise possible, and this is not standard behaiour, especially on a retail end user system.

 

Yesterday, I discovered that my friend laptop - a BENQ brand - has 1x1G + 1x2G RAM modules. Therefore, your saying that the system cannot run 2 different RAM modules seems not correct.

 

You can run different modules, on either channel. 1x1GB on Channel 0 and 1x512MB on channel 1 for example. You can't put 1x1GB+1x512MB on channel 0 and the same on channel 1, the mismatch will cause the bus to drop to single channel mode.

It depends on the chipset too, on some systems you must match speed AND size to operate in dual channel mode.

 

My wording was off is all, you just can't run in dual channel mode with mismatched RAM.