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It seems quite a few PC suppliers do exactly the same trick. I recently upgraded someone's RAM on their Dell XPS system and was disappointed to see that all 4 slots were taken up with 1 GB, 667Mhz sticks, even though the system supported 800 Mhz RAM. The intention was just to upgrade to 6 GB, but they had to replace all the RAM anyway so ended up going for 8 GB just to be thorough.

Dell didn't get any of the money though since the memory was ordered from Crucial.
 
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