@henribarbu
The SIMMs were fully tested before despatch. We generally put all memory through a Pre-Delivery Inspection which tests the integrity of the memory. We don't want memory to go all the way to Belgium untested and turn out to be faulty. In this case the memory passed the PDI- so you know they are 100% OK.
The 2x SIMMs were tested in a Blizzard '040/210Mhz- ensure that you change the wait states to ON and precharge to ON in the Early Menu on the BlizzardPPC. Then test the SIMMs, one-by-one in your BlizzardPPC. Also test them one-by-one in each slot separately.
You should find that the memory then works OK. Any queries, please contact us.