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What are UTT Memory ?


Friday, July 8, 2005

In recent months,  there seems to be an increased buzz on UTT based memory modules. What exactly is  UTT memory ?  UTT stands for UnTested DRAM chip. This term is used on chips which are packaged in the final backend assembly but not speed graded and sorted according to the frequency and latency categories .

There are much misconception that UTT memory modules are new and high frequency DRAM chips  that just hit the market. UTT are essentially untested DRAM chip.

DRAM manufacturers are regularly releasing these UTT DRAM chips in large volume into the market distribution. There are a number of reasons why DRAM manufacturers are choosing to release the untested chips into the DRAM Spot market  

One of the benefit of shipping untested Dram chips translate to  "cost savings" as DRAM manufacturers can cut up to 20 percent in cost per DRAM chip by skipping chip detailed reliability burn-in and functionality testing on higher end chip testers  . This effectively save time, production test capacity and shortened production cycle.

Many DRAM makers outsourced the DRAM chips testing to 3rd party testing contractors and there is a cost involved for each chip whether it is tested good or bad. In DRAM wafer fab, each DRAM wafer can be advanced probed for defects and non-conforming test to determine the yield before final packaging . The wafer with poorer yield are marked and package into chips destined to be sold as UTT chips.

Imagine the huge losses a manufacturer can incurred, if the under-performing wafers are scrapped.  UTT chips are the "creative" effort of DRAM manufacturers to turn scrap losses to profit.   Effectively enabling DRAM manufacturers to eliminate large quantities of untested and non-conforming chips into  the market very quickly for non-PC applications such as DVD players, MP3 players, toys and low-end graphic display cards.........etc. This can be quite an sound business model if the supply of UTT chips are consistent.

This spot price was taken from www.dramexchange.com , notice the DDR256Mb 32Mx8 ETT UTT price are listed as a commodity item. ETT is a new term known as - Effective Tested Chip which means used the same as UTT.

Most of the UTT chips are shipped blank without any noticeable marking on the chips, memory brokers buys this chips at very low price for trade.  UTT chips are traded worldwide do end up in memory module manufacturing facilities worldwide for eventual assembly into Memory module application.

UTT devices are commonly seen in inexpensive or low end memory module . The frequencies and latencies varies from different batches thus requiring pre-sorting by memory testers before production assembly. In Asia, there are over several hundred small scale companies emerging selling UTT and Downgrade DRAM products.

A Typical Unmarked 66pin DDR TSOP ( UTT ) or Downgrade chip

Majority of the UTT chips are used with low end PCB board . These UTT chips finds its way to lower end DIMM modules which are often tested only on motherboards . The tested modules are then imprinted with the respective company logo or laser imprint .  Most 3rd Party manufacturers print some label that has no tracebility back to the origins of the DRAM chips.

For the lower performance DIMM module , these are typically sold with standard labeling to consumer at rock bottom price.

UTT Chips assemble on DDR DIMM PCB board ( Chips are Winbond BH-5)

For the better performing UTT chips, most common practices are enclosing the modules with an attractive HeatSpreader, to make the DIMM modules look more appealing to the consumer.

Typical Copper Plated Heat-Spreader

It is not uncommon to see higher performance modules build with UTT Dram selling for premium price and for very high performance application. For instances , some websites are offering very high price DDR 500 Mhz 184pin Unbuffered DIMM memory running with 2-2-2 peak performance level, requiring at least 2.6 - 3.5 Volts to support this special high performance module on selected Motherboards offered by MSI,Gigabytes, ASUS......etc.

High Performing Unbuffered DDR 500Mhz DIMM using UTT Chips with Heat-Spreader

The Winbond BH-5 chips are legendary ,the frequency of the chip can be scale beyond its rated frequency as the voltage level is raised. There are reported cases of the Bh-5 and Bh-6 chips capable of clocking at 600Mhz data-rate with very low latencies. A typical example of a high performing 3rd party DIMM module capable of overclocking beyond 500Mhz , the latency are offered in the following :

All rated timings listed is CAS-tRCD-tRP

2-2-2 means : Cas = 2 , Trp = 2 , Trcd = 2

To find rated MHz from ns, ( 1/ns x 1000 ).

PC2700 = DDR333
PC3200 = DDR400
PC3500 = DDR433
PC3700 = DDR466
PC4000 = DDR500
PC4200 = DDR533
PC4400 = DDR550
PC4800 = DDR600

DRAM industry players are not overly concerned about UTT memory module damping prices, since the flow of  UTT chips into the main stream grey-market distribution channel can be regulated depending on the supply and demand of dram chips. 

In the real world application,  memory modules built with UTT chips may not perform with great reliability, thefore consumer often seeks for more reliable memory module build by first qulaity chips neccessary for mission critical application such as Server or highend Workstations.

With DDR2 Memory emerging as the next main stream memory wave , will there be any UTT DDR2 chip available ? The answer is 'Yes',  there will always be UTT chips and downgrades dram chips  irregardless of any new memory technology

The next time you find a computer advertisement in your local paper offering a 1GB Unbuffered DDR DIMM at $49 bucks or a 600Mhz DDR DIMM with a Flashy Heat-Sink  , chances are this module are made with UTT chips . One gets what one pay for , so do not expect longetivity of memory module in this category.

 

By: DocMemory
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