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DDR4 Heir-Apparent Makes Progress

3/11/2014 10:15 AM EDT
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resistion
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TSV cost reduction
resistion   3/11/2014 9:29:21 PM
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What is the plan for TSV cost reduction? Is it the TSV fabrication that is the key cost or TSV-related integration into the product (like testing)?

alex_m1
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Re: how does this relate to servers?
alex_m1   3/11/2014 6:13:18 PM
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Since each hmc has 8 layers of dram, my guess is that for first version they prefer to use old manufacturing lines and get some money from them, instead of taking a risk a reusing new manufacturing lines.

 

TanjB
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how does this relate to servers?
TanjB   3/11/2014 3:54:36 PM
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The size of the modules (2GB) makes this look like a technology for local GPU memory or perhaps even for mobile devices.  But servers?  How does this add up to 128GB or more seen on modern servers?  Is there something else in plan for that market, or does that remain DDR4 territory?

TanjB
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Re: DDR4 replacement??
TanjB   3/11/2014 3:52:06 PM
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Power costs at 10 cents/kWh are about 80 cents per year per watt.  Many data centers have lower contracts than that, but should add in overheads to build the power distribution and substation so it is on balance a fair estimate.  A 200W server (which includes the overhead ratio for a modern DC) is costing about $160 per year for power.  This puts the cost of power under 10% of operating costs.

The bigger cost is opportunity cost.  A DC is generally built out to the max power the site can obtain, so every watt in that 200W must be optimized.  If you add 1W in DRAM then you subtract 1W from something else.  Each W thus has an opportunity cost of about 0.5% of the server which more like $10 per year.

So, you have the right conclusion, but it can be helpful to have a better model of why.

Components which save power in the server market are definitely valuable.  Each W saved is worth dollars, so long as performance is not compromised.

alex_m1
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Re: DDR4 replacement??
alex_m1   3/11/2014 1:47:37 PM
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Let's look at rought cost estimates of cloud computing:


Power related costs are nearly 40% of total, with saving in memory power could reduce 15% of those 40%, meaning 6% of total.

Since server costs are 50% of total ,those saving comes down to 3% of server cost.

Dell charges for a "performance" server $4100K :

"Dual Intel® Xeon® E5-2620 processors, 16GB memory, 500GB hard drive and 3 year ProSupport warranty"

http://www.dell.com/us/business/p/poweredge-r720/fs

 

3% * 4100 = $123 = $7.6 per GB of power savings (without speaking about other benefits). Considering the fact that DDR(consumer- serever costs more) costs $11.5 per GB , those power savings look like a good reason for adding an HMC to a cloud server even as main memory. 

TarraTarra!
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DDR4 replacement??
TarraTarra!   3/11/2014 1:02:52 PM
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HMC, HBM and other technologies are certainly very interesting but I dont see how they would replace commodity DDR4 DRAM anytime soon. Am I missing something here?

 

The cost/bit of DDR3/DDR4 will continue to be much lower than what HMC/HBM will offer for a long time. HMC and HBM do offer interesting possibiities with on-die memory stacking, fast look-aide memory but will they replace DDR4 a the main memory for processors?

 

 

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