My 1501 comes with 1GB (2x512).  I bought a 1GB module with Hynix chipset PC5300, and replaced one of the 512MB module to see if it works.  XP recognizes the total amount of memory installed as 1.5GB, and it seems to work without a problem.  Running Photoshop, 3DMark, Sisoft Memory Benchmark without a problem.  Only Performance Test 6.0 seems to have problem with Memory Allocation Error.    Now, I know the manual says it supports 512MB, 1GB & 2GB, but it doesn't say whether the memory should be installed in pair.   I tried to use only the new module in 1 slot, and the problem persists.

 

My question is, should the memory come in pair of the same size in 1501 ?

Can it use 1 memory module only  ?

I want to know where the problem comes from, whether it is caused by unsupported configuration, broken new memory, incompatible memory, or what.

 

I can buy another 1GB module if what it takes to run reliably, but I need to be sure that the problem is not caused by incompatible memory.  I really need advice.