On Thu, 25 Nov 2010 23:46:04 -0500, Paul <(E-Mail Removed)> wrote:
>>The Seabat wrote:
>>> I have the Gigabyte GA-880GA-UD3H motherboard and I'm looking to buy
>>> some RAM for it. Will this board support DDR3 1600 RAM? The compatible
>>> RAM list from their site says it will, but the specs that came with
>>> the MB don't mention it. The manual just says ". . . Support for DDR3
>>> 1866(OC)/1333/1066 MHz memory modules". So I'm kinda in a quandary
>>> about this. Can anyone shed some light please?? Thank you.
>>>
>>>
>>
>>So you're wondering whether intermediate values are possible ?
>>
>>You can start by looking at the user manual for your motherboard.
>>The RAM timing section indicates it has four settings (dividers).
>>Combined with that, would be doing things like changing the CPU
>>input clock. If you bump up the CPU input clock, bump down the
>>CPU multiplier, bump down the HT multiplier (to remain within
>>spec), then memory values above stock should be possible. That's
>>how you manage to get over 1600. I think the AMD stock may be
>>1333, with the possibility that four sticks runs slower than
>>two sticks (I'd verify this for you, if AMD still had any kind
>>of data sheet). Maybe if you install four sticks, you run it
>>at 1066 ?
>>
>> RAM Divider "DDR Rate" (memory clock value as seen in CPUZ)
>>
>>Nominal x4.00 DDR3-800 (400)
>>CPU Input x5.33 DDR3-1066 (533)
>>= 200MHz x6.66 DDR3-1333 (667)
>> x8.00 DDR3-1600 (800)
>>
>>Faster RAM will also run at slower speeds, no problem. So imagine
>>that you're not happy with the conditions to run at DDR3-1600
>>(the rated speed of the RAM). You can always leave the processor
>>at stock, and select DDR3-1333 in the BIOS screen, and run the
>>DIMM at 1333. It will run fine below the rated clock. So a
>>fast DIMM, like DDR3-2000, could be used for overclocking
>>experiments, as well as running at AMD stock of DDR3-1333.
>>
>>The timings (tRAS, tRCD, tCAS and the like), are measured in
>>"ticks". Like CAS7, means 7 clock cycles. The clock cycle in
>>that case, is the speed the DIMM is running at (800MHz on the
>>DDR3-1600 DIMM). The clock period of an 800MHz clock
>>is 1.25nanoseconds. So 7 * 1.25ns = 8.75 nanoseconds.
>>The timing parameter in question, might be a "minimum allowed
>>time". Now, when you change the memory clock (either above or
>>below its stock value), that changes the clock period. Then
>>you have to re-solve the equation: ??? * 1.5ns = 8.75 nanoseconds.
>>In other words, the timing values, have to be compensated for
>>the clock being used. The DIMM itself has a timing table stored
>>in the SPD. It might say DDR3-1600 CAS9, DDR3-1333 CAS8 or whatever.
>>If you're going to be using values which are not in the internal
>>table of the DIMM, or setting everything up manually, it's your
>>responsibility to scale the timing numbers (the 7-7-7-21-whatever)
>>thing, according to the clock used. If you don't make the adjustment,
>>the computer could crash or hang in the BIOS or sooner. Clearing
>>CMOS will allow you to recover from the blunder (some motherboards
>>recover on their own, and reset the BIOS after a crash, but
>>the CMOS jumper covers the case of really bad crashes).
>>
>>Always unplug the computer, when using the clear CMOS jumper. With
>>any luck, the manual will warn you about this.
>>
>> "Always turn off your computer and unplug the power cord
>> from the power outlet before clearing the CMOS values."
>>
>>It helps, if you're going to be doing manual settings, to find
>>an article on the web that describes the "clock architecture" of
>>your processor. That is necessary, so you can understand, when you're
>>changing the CPU input clock, what parts of the processor are also
>>overclocked (whether you wanted it or not). The latest AMD processors,
>>have CPU core clock, uncore clock (internal Northbridge/L3 cache),
>>and memory clock. It pays to understand how they're related, whether
>>they change in a dependent or independent fashion or not. While I
>>found one site that attempted to explain it, they seemed to be missing
>>good info on the uncore.
>>
>>The AMD processors now have more than one power plane. When the uncore
>>thing was introduced, the Vcore circuit around the processor was
>>split in two pieces. You might see five phases, but the circuit
>>configuration was "4+1". That means 4 phases powered the CPU core,
>>1 phase powered the uncore and L3 cache. A separate circuit, near the
>>DIMMs, might provide DIMM power (and also power the bus drivers on the
>>processor memory interface). So again, it helps to understand how
>>the power is generated, whether you can adjust the uncore voltage
>>separately and so on. Apparently, if you bump the memory clock,
>>it may be profitable from a performance perspective, to change
>>the uncore clock and operating voltage. It's actually a bit complicated.
>>But if you want to go "non-stock", you should at least understand
>>a little of it, so you'll understand why the computer is
>>crashing.
>>
>>Some BIOS, when you use their built-in overclocking functions, will
>>do the hard work, like making minor adjustments to the uncore for
>>you. But at the same time, some of these BIOS have also been known
>>to do nutty things. Which is why, the sentient operator always has
>>to be on the lookout for surprises :-)
>>
>>If I'm reading the manual right, 1600 should be easy to get, and
>>1866 may require more research to do it right.
>>
>>Good luck,
>> Paul
Thanks Paul. If I understand you correctly, I can run the DDR3 1600 at
the slower 1333 speed without any problems (except lower RAM speed).
Good. I'm not into OC'ing. . . yet! But I might someday and the info
you posted has been saved and I will refer to it. I love it when I
learn more than what I asked for! Thanks again.
--
The seabat
Filtering GoogleGroups & Goobers with extreme prejudice!
Usenet Improvement Project: R.I.P. Lee aka Blinky the Shark
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