Question about RAM compatibility

[KerbMav]

Could I (under Win7 64bit) safely use these 2x2GB with my left over 2x1GB on this mainboard for 6GB of RAM total?

4GB 800MHZ DDR2 NON-ECC CL5

Kingston HyperX KHX6400D2B1K2/4G

DDR2 2048MB (2X1024) PC1066

Corsair TWIN2X2048-8500C5D

P5K/EPU S775 P35 ATX DDR2

ASUS 90-MBB67A-G0EAY00Z

[shand]

i dont think so. try it though, nothing explodey bad will happen - if they arent compatable either the machine will let out a series of beeps and fail to boot, or it will just ignore any that arent compatable with the first slot.

all three are DDR2 so theres some hope they'll work.

the best indication would be the speed - the first is 800Mhz, but the second is 1066 Mhz i beleive the last is also 1066. this speed difference may cause issues, or it may just mean they run very slightly slower.

Lastly it depends on what version of windows 7 (apparently) starter is still limited to 2gig (apparently), but anything else is at least 8 gig. (on 64 bit systems)

[SleepingDragon]

It will run at the speed of the slowest installed RAM memory.

[Bean]

Yeah, just make sure you installed them colour coded, so both 2G sticks in one colour, both 1G sticks in the other. If there are any indications as to which is slot0, I think the 2G sticks should be 0 and the other corresponding colour. (Or slot 1 if it's labelled 1,2,3,4 instead of 0,1,2,3)

Edit: if this is your mobo: http://www.asus.com/au/Motherboards/P5KPLEPU/#specifications

Then it says max 4GB RAM

Also:

4 x240-pin DIMM, Max. 4 GB, DDR2 1066(O.C.)/800/667 Memory

Dual Channel memory architecture

*Support max. 2 DIMM modules only for yellow DIMMs when over-clock to DDR2-1066

*When installing four DDR2 DIMM modules, install only single-sided memory modules.

In which case using the 4G would be your best idea, as it is within normal spec for the mobo and more ram trumps ram speed in most cases at/under 4GB

And install the 2x2G in the Yellow, regardless of if you try for 6G or not

Edited August 12, 2013 by Bean

[KerbMav]

My main question at the moment is, can I run one pair with 2.1 and the other with 1.8 Volt - and if not will undervolting mess up latency or anything?

[Bean]

Didn't notice the voltage, if the 1066 stuff is the 2.1V stuff you'll probably get away with it at 800MHz, again, if that is your mobo, 4G is the max, and make sure you check your bios and make sure it's 1.8V 800MHz if you try, otherwise you're in with a chance to fry the 1.8V stuff, or get instability due to the 800MHz stuff running overclocked

[Nuke]

the trick is to play around with timing till you can find something that makes all the ram chips happy. its a lot of tweak, memtest86, tweak some more, memtest86 again, wash, rinse, repeat. when you can find high performance settings and pass memtest86, you are done. i think i spent several hours trying to get the most out of my ram when i built this rig. now when you stick two differently speced sticks in and try to run them together, you usually have to cripple your highest performance ram so that you are not demanding too much from the low performance ram (which causes errors). if i had to choose between lower memory latency and more ram, id choose the lower latency.

Edited August 13, 2013 by Nuke

[Bean]

Nuke: Considering just how much of a memory hog Windows 7 + programs tend to be, 2GB of ram may not be the better choice, 16GB vs 8GB of lower latency I'd understand, that said RAM doesn't make nearly as much of a difference as CPU/GPU.

There's a fair chance the point is moot though with that mobo as it looks like it supports a max of 4GB.

KerbMav: I don't think you can do any damage without overvoltage/overclocking the RAM, so if it works with 6GB you can then try tweak, memtest86, etc.