Omega Owners Forum
Chat Area => General Discussion Area => Topic started by: The Barge Captain on 18 December 2008, 14:10:32
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I've been considering upgrading the amount of RAM in my Dell Dimension 5100 desktop, but all i know is that it has 512 Mb in it at the moment.
I've been on Dell's website, and it tells me that the package type is
"DDR2 240-pin DIMM, SDRAM-DDR2"
Am I an idiot, or is this 2 different types?
A 2Gb upgrade would be good so I assume I need to buy 2 x 1Gb memories?
All advice greatfully recieved.
Thanks.
Would this work?
http://cgi.ebay.co.uk/GEIL-2GB-DDR2-667-CL5-0-DUAL-CHANNEL-BRUSH-ALUMINUM-RET_W0QQitemZ120350596338QQcmdZViewItemQQptZUK_Computing_ComputerComponents_MemoryRAM_JN?hash=item120350596338&_trksid=p3286.c0.m14&_trkparms=66%3A2|65%3A1|39%3A1|240%3A1318
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According to the memory configurator from where I buy my components (bluepoint), you can have a max of 4gb. Installed in banks of 2.
If you are after 2gb, 2 of these will do the trick. But just in case, check with them before ordering.
http://www.ebuyer.com/product/106114
HTH
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I was keeping any eye on this thread because I was wondering if the fact that these were CL5 would make 'em slow... I seemed to recall that a latency greater than 3 was not to be used.
Disclaimer: I may well be talking out of my backside.
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Depends on the memory
As a guide
DDR - CS (CAS)2-3
DDR2 - CS 3-5
DDR3 - CS 7-9
Are about the standard
The CL rating is the number of clock cycles you have to wait between chip select being raised and the data on the bus being valid!
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Depends on the memory
As a guide
DDR - CS (CAS)2-3
DDR2 - CS 3-5
DDR3 - CS 7-9
Are about the standard
The CL rating is the number of clock cycles you have to wait between chip select being raised and the data on the bus being valid!
Aha! Ta.
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I was keeping any eye on this thread because I was wondering if the fact that these were CL5 would make 'em slow... I seemed to recall that a latency greater than 3 was not to be used.
Disclaimer: I may well be talking out of my backside.
As MDTM says, the newer memory technologies have higher latency. CL5 for 667Mhz and CL6 for 800Mhz seems to be around normal for consumer
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Also, try Crucial - they make it easy to buy memory, free delivery, overall works out same cost as the box shifters, but I've never had any issues with the company or the memory :y
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Yes....it just high lights quite nicly how doubling the clock speed does NOT double the throughput!
So although the clock speed is higher, it takes more clock cycles to complete a RAM access so rather than a x2 gain, you might get a 20% or so improvement! :y
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Depends on the memory
As a guide
DDR - CS (CAS)2-3
DDR2 - CS 3-5
DDR3 - CS 7-9
Are about the standard
The CL rating is the number of clock cycles you have to wait between chip select being raised and the data on the bus being valid!
So the lower the cl number the better then?
Presumably the higher the clock speed the better also?
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Depends on the memory
As a guide
DDR - CS (CAS)2-3
DDR2 - CS 3-5
DDR3 - CS 7-9
Are about the standard
The CL rating is the number of clock cycles you have to wait between chip select being raised and the data on the bus being valid!
So the lower the cl number the better then?
Presumably the higher the clock speed the better also?
As a rule of thumb....yes.
What you have to consider is that DDR ram is DDR ram.....the 1-2-3 bit is related to a (jedec I think) spec which describes the bus speeds and the pinout to standardise the footprint (which on most configs describes where the polarising notch is!).
So....consider a 400Mhz DDR ram with a CAS of 2......and compare it to a 1200Mhz DDR3 with a CAS of 6.....performance wise they will be pretty much the same!
Which is actualy no real surprise as they probably use the same RAM chips.
So.....you want the fastets clock speed (which is part of the standard so DDR2 or 3) and the lowest CAS.
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OK. With you so far.
What about where items are speced as having timings such as 4-4-4-12?
What does that mean?
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OK. With you so far.
What about where items are speced as having timings such as 4-4-4-12?
What does that mean?
Ok, we are now gettting beyond the 10,000m view so here goes
What you need to understand is how DRAM is accessed.
The best way to picture it is as a spreadsheet with rows and columns and each cell contains your stored data. Each row is a bank of memory
For the CPU to access memory, it first must determine which row or bank in the memory is to be accessed (which is DIMM in most domestic PC cases and described as banks) and then activate that row with the RAS signal. Once the start address of the data has been setup then it can access that row (or bank) sequentialy over and over until the data is exhausted without re-writing a new address value.
Sooo..
The values (in clock cycles) relate to a-b-c-d where
a= The CAS latency which is as above....i.e. its the time between the CAS signal being raised on the device and the data being requested being valid on the devices pins. - This is the only major figure to consider for normal use.
b= tRCD is the delay from the time a row is activated to when the cell (or column) can be activated by the CAS signal.
c- tRP is the time required to terminate one row access and begin the next row access.
d=tRAS - This is the time required before (or delay needed) between the active and precharge commands. In other words, how long the memory must wait before the next memory access can begin.
So, with the above.
CAS is key as it is a value that plays a part in EVERY memory read!
tRCP and tRP only come into play when changing between rows/banks which you would like to think is not very often but, sadly the operating systems are not that clever when it comes to memory mangement! You can however consider it considerably less significant than CAS
tRAS is only significant when moving to a different address within the same Row/Bank. Sadly again, memory management is not this clever in most operating systems!
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So would 2 x 2gb, or 4 x 1gb of ram make any difference to memory access on a 4 slot motherboard.?
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Still with you (just), but to summerise then, again lower numbers are better?
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So would 2 x 2gb, or 4 x 1gb of ram make any difference to memory access on a 4 slot motherboard.?
Again, dependent on the motherboard and specific way the memory is built etc but....2 x 2Gb would generally be better as you have fewer opportunities for bank changes
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Still with you (just), but to summerise then, again lower numbers are better?
Yes....but CAS is the key one so hence something with 5-5-5-10 will be better in the real world than something with 6-4-4-8
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Mine is CL5 (1066)
But doesn't detail the n-n-n-n