How much faster is RAM compared with a solid state HD?

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  • #1
Simfish
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Main Question or Discussion Point

If the difference isn't that much, then could a computer theoretically have A HUGE amount of RAM, simply by setting aside a significant portion of the SSD as virtual memory? Maybe a SSD external HD could also be used as virtual memory (for those of us who don't have internal SSD drives yet)
 

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  • #2
DaveC426913
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If the difference isn't that much, then could a computer theoretically have A HUGE amount of RAM, simply by setting aside a significant portion of the SSD as virtual memory? Maybe a SSD external HD could also be used as virtual memory (for those of us who don't have internal SSD drives yet)
Problem with RAM is that it's volatile. Goes away when the power goes off.

I'll wager that the price one pays for permanent storage, is that storing something in a permanent matrix takes time.
 
  • #3
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Although more RAM is a good thing generally, after a point it becomes a hindrance to the system (until they bring out a new motherboard & OS to handle more). The current max for an OS such as Windows is 8GB.

As Dave points out, RAM is wiped when the power goes off. Because you don't have to physically write it to a disc, it is quicker.

An SSD as a virtual memory source, would prove quicker than a regular HD, but it would still be slower than RAM.

My computer can work with 3GB of RAM quicker than it can write to my 1GB memory stick.
 
  • #4
Hepth
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Fastest SSD (OCZ Z) = 1400 MBps
DDR3-2500 = 20,000 MBps
 
  • #5
Borek
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Problem with RAM is that it's volatile. Goes away when the power goes off.
It is even worse that that, at least in the case of dynamic RAM. It needs constant refreshing even when on.
 
  • #6
Simfish
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Ah yes. I think my question was a bit confusing. What I meant by "A HUGE amount of RAM" was actually something that might approximate a "HUGE amount of RAM". Would it be feasible in the near future? Or is the difference between SSD speed and RAM speed *far* greater than the distance between SSD speed and speed of, say, a 7200 RPM drive?
 
  • #7
phyzguy
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If the difference isn't that much, then could a computer theoretically have A HUGE amount of RAM, simply by setting aside a significant portion of the SSD as virtual memory? Maybe a SSD external HD could also be used as virtual memory (for those of us who don't have internal SSD drives yet)
The answer to your question is that RAM is hugely faster. A typical SSD has a random access time of ~100 microseconds, while typical RAM has access times of a few nanoseconds or even less for onboard RAM. So the RAM is thousands to millions of times faster. You would not like performance of your computer if you used the SSD for main memory. The trade-offs between speed, cost, power, and volatility is why computers have evolved to have a hierarchy of memory - from fast, expensive, volatile, and power-hungry onboard cache memory to slow, cheap, non-volatile HDD or SSD.

Note that Hepth's comment is only part of the story. It is not just the data rate that is important - random access time is critically important too.
 
  • #8
Although more RAM is a good thing generally, after a point it becomes a hindrance to the system (until they bring out a new motherboard & OS to handle more). The current max for an OS such as Windows is 8GB.
Wut??? Please elaborate. What do you mean by 'after a point'? and where do you have the 8GB from?
 
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  • #12
Mech_Engineer
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Although more RAM is a good thing generally, after a point it becomes a hindrance to the system (until they bring out a new motherboard & OS to handle more). The current max for an OS such as Windows is 8GB.
That's only true if you're running Win 7 Home Basic 64-bit. Win 7 Home Premium supports 16GB, and Professional/Enterprise/Ultimate all support 192GB. It's pretty common for consumer-level motherboards to support 16GB of RAM these days. usually the limitation is 4GB per stick, and the number of ram slots (Intel LGA 1366 boards usually have 6 slots, so they usually suport 24 GB).

Windows 7 Physical Memory Limits


Windows XP x64 is limited to 128GB

Windows XP Physical Memory Limits
 
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  • #13
Borek
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Updated: February 9, 2005
I doubt anything changed with the systems in question. If you have read the page, depending on the OS version up to 64GB were already supported several years ago.
 
  • #14
I doubt anything changed with the systems in question.
ofc not, but the statement was about windows in general. A standard windows PC comes with windows 7 64 these days. And yes, a standard motherboard is 16 max, but for a few dollars more, you can get one with 24 or 32.

If you have read the page, depending on the OS version up to 64GB were already supported several years ago.
yes, I've read it 5 years ago or so. ^^
 

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