The UTT as per the statement claimed here is not true.
UTT is untested memory, but it has yield guarantee by the wafer foundry like Samsung, Hynix and etcs.
Normally the guarantee is 80 to 95% from the wafer foundry so that the wafer foundry can save
1. Testing cost and wafer probing cost
2. Wafer probing/testing error is about 2-5%. Means, during the wafer probe, the consistency of the location/pin continously probe at the same tested area has some variable scope. Therefore it will create the lost of 5% of the quantity chips per batch.
Testing error, it happens for the same reason.
3. Time to market issues - the normal cycle of wafer being fabricated out to market, takes at least 3 to 4 weeks and this is subjected to the schedule/avaibility of the production of wafer probe and test
4. Each test under Advantest is very costly. We call it ATE = advance test equipment. for 64pcs test jig or 64pcs test equipment it costs usd5 to 8 millions. And the testing time is very long.

Therefore, for the production scheduling, demand and supply, the factory guys will give the UTT to the memory modules guys such as Kingston, Apacer, Kingmax, Corsair, OCZ, and etcs.

So if the UTT is not good , do you think kingston is good? kingmax? corsair?


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Added on March 6, 2008, 11:32 amMar 4 2006, 09:50 AM Show posts by this member only | Post #39


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Er... 1-sided RAM means that you can only find a number of chips (usually 4 or 8) on a side of the DIMM module but none on the other side. 2-sided RAM means that there are chips on both sides.

For DIMM module, 1-sided RAM means that it'll occupy 1 memory bank on your motherboard's RAM slot, while 2-sided RAM occupy 2 memory banks. However, 1 DIMM module (no matter 1 or 2-sided RAM) uses up 1 RAM slot on your mobo.

The differences between "1-sided / 2-sided" rams are as follow:
1) 1-sided RAM usually has denser capacity compare to 2-sided RAM (eg. 512MB RAM = 64Mx8 on 1-sided RAM = 32Mx16 on 2-sided RAM)
2) 1-sided RAM usually has higher latency compare to 2-sided RAM, due to larger capacity. (Those premium RAM usually comes in 2-sided RAM)
3) 1-sided RAM is harder to manufacture, due to larger capacity
4) 1-sided RAM use up less memory banks on your mobo. Some mobos cannot support 8 memory banks, which means that you can't use 4 2-sided RAM at once.

I guess that's about 1-sided/2-sided RAMs



my comments:

1. normally 1 sided is : for 512MB RAM = 64mx8 with 8 chips, 2 sided will be 32mx8 with 16chips. For notebook memory or graphic card, 32mx16 is used to increase the performance which means 16bits are used rather than 8bits per single clock pulse.
2. not neccessary 1 sided ram has high latency.it depends on the fabrication process, technology, prices + testing cost. All need to factor in before u produce or manufacture
3. not neccesary and not true. But the testing and probing time will be double but doesnot mean it is harder. Yes it is harder for wafer foundry but not the memory manufacturer like kingston or corsair..or anyone.

in fact, looking back at 1 or 2 sided,
if you have 8 chips versus 16chips ..with 1 byte of data out...8 chips will be having more stressful than 16chips. Therefore, when comes to the memory 's heat problems, 8chips has more heating up problems.
Therefore, 16chips is better. But due to the cost factor, 8chips is much easier to assemble coz requires less passive components. Hence factory can earn more.


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This post has been edited by Q2modules: Mar 6 2008, 11:32 AM