Need help with ram

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FILEON

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Dec 19, 2014
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I have 2x2gb 1333mhz ram and recently I bought 1x4gb 1600mhz.When I plug them, the PC starts normaly, but when I restart my PC it wont boot. I tried changing them with 1x2gb and 1x4gb and it is still the same.
 
Solution
Tradesman1
Best bet is the 4GB in slot 1 and the 2GB sticks in slots 3-4 - that will maintain dual channel w/ all 8 GB if the mobo supports flex, also may need a little additional DRAM and/or MC (memory controller) voltage added, maybe try + 0.05 to each for starters. If you split them as Brispuss suggests it's more stress on the MC as only 4GB will run dual and the 4GB stick will be running in single channel mode
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Install just the 4GB module and see if boots. Btw, what is the model number of your PC?
 
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with just 4gb(2x2GB or 1x4GB) it boots normaly, yesterday I put 1x2GB and 1x4GB and it works fine. Then I tried to add the other 2GB ram and it boots the first time but next time it fails
 
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One 2 GB DIMM should be in slot 1, the other 2 GB DIMM should be in slot 3, and the 4 GB DIMM should be in slot 2 or in slot 4.

Alternatively, one 2 GB DIMM should be in slot 2, the other 2 GB DIMM should be in slot 4, and the 4 GB DIMM should be in slot 1 or in slot 3.
 
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Best bet is the 4GB in slot 1 and the 2GB sticks in slots 3-4 - that will maintain dual channel w/ all 8 GB if the mobo supports flex, also may need a little additional DRAM and/or MC (memory controller) voltage added, maybe try + 0.05 to each for starters. If you split them as Brispuss suggests it's more stress on the MC as only 4GB will run dual and the 4GB stick will be running in single channel mode
 
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Solution
With 4 GB in slot 1, and 2 GB in slot 3 and another 2 GB in slot 4, and IF the motherboard supports Flex mode and IF the memory controller otherwise accepts the DIMM's (capacities and chip architecture) in this configuration, then 2 GB of the 4 GB will run in dual channel mode with the 2 GB in slot 3. The remaining 2 GB of the 4 GB in slot 1 should run in single channel mode, and the 2 GB in slot 4 should also run in single channel mode.

So we should still have 4 GB in dual channel mode, plus 4 GB in single channel mode with the above configuration.

I would suggest this configuration is more stressful on the memory controller as it has to use Flex mode IF available. My configurations do not require Flex mode.

IF Flex mode is not available on this motherboard, then all of the DIMM's in the above configuration would run in single channel mode (DIMM specs and memory controller permitting). However, the OP stated having problems with running all of the DIMM's at the same time, so it is likely the DIMM specifications are not entirely compatible with the memory controller, depending on how the DIMM's are installed in the slots.
 
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________________

Sorry but wrong....slots 1-2 compose the A channel, slots 3-4 are channel B - with what I suggested you have 4GB in each channel and under flex (An Intel enhancement that has been around for years - Flex looks at the total amount of DRAM in the channel (i.e. it doesn't differentiate between slots as you imply) or if AMD which has their own adaption of Flex the same happens - it looks at the total DRAM in the channel - not by individual slots.

Further as I mentioned it will probably take additional DRAM and/or MC voltage to get them running smoothly - this too has been around for years, especially in use when mixing sticks or trying to, as well as to aide the MC when it is on the weaker side
 
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Sorry, but disagree.

Unless this is an unusual motherboard, most motherboards slots 1 & 3 are used for one dual channel, and slots 2 & 4 used for the other dual channel.

My understanding is that Flex mode looks at the two DIMM's inserted in the dual channel slots. Now for dual channel operation, the DIMM memory capacities have to be the same (regardless of Flex mode or anything else). The system sees 4 GB in slot 1, say, and sees 2 GB in slot 3 (slots 1 & 3 being one of the dual channels). If Flex mode is available, then provided the chip architectures, voltages, (and to a lesser extent the speeds and timings) are similar, then the system will use 2 GB of the 4 GB DIMM in dual channel configuration with the 2 GB DIMM. Again, the remaining 2 GB from the 4 GB DIMM will be in single channel mode.
 
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As I explained, Intel's flex as well as AMD for the last few years looks at total amount of DRAM in a channel - not a particular slot - the fact that a Channel has 2 slots doesn't mean it looks at each slot as an individual thing. If you don' believe me try it. DRAM is probably the least understood component in a rig. I've literally helped hundreds of folks here at Tom's in the last year and a half with this exact problem of mixing sets and sticks of DRAM
 
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