Member Avatar for sgunnery

I currently have 8GB installed (2x4GB) and am wanting to add another single 8GB stick to give me 16GB but the CAS timing on my RAM is 9-9-9-24 and the new one is 10-10-10-27 the make is the same would this be possible to add the single 8GB stick or would this cause issues??

Thanks for any answers

  • 6 Contributors
  • 7 Replies
  • 1K Views
  • 2 Months Discussion Span
  • Latest Post Latest Post by sheikhali449

Dani AI

Generated

Short answer: adding a single 8GB DIMM to an existing 2×4GB set will usually work, but how the system uses that memory depends on the memory-controller and slot population. Modern Intel/AMD controllers support an asymmetric or "flex" mode: the matching portion of each channel runs interleaved (dual‑channel) while the leftover capacity runs single‑channel. Expect the motherboard to pick conservative (slower) SPD timings when modules differ. (edc.intel.com)
(See Intel's memory-organization notes and a plain-language flex explanation: Intel memory controller organization and Tom's Hardware: What is Flex Mode?.)

Practical checklist (do these after powering down and installing the DIMM): make channel totals equal if possible — on a 4‑slot dual‑channel board put the 8GB on one channel and the two 4GB sticks on the other so each channel totals 8GB. After boot, confirm Channel # and real timings with CPU‑Z, and run a full memory check (MemTest86) to rule out instability. If you see single‑channel or instability, try swapping slots, set memory to SPD/default (disable XMP/overclock profiles) and test one DIMM at a time. (www2.cpuid.com)
(CPU‑Z download / info, MemTest86 test tool.)

Caveats: 8GB sticks are often dual‑rank and some older boards or IMCs limit rank/density — mixing ranks or registered/ECC vs non‑ECC modules can reduce speed or prevent boot. Also watch voltages (DDR3 vs DDR3L, DDR4 XMP profiles). If predictable peak performance matters, matched 2×8GB kits remain the safest choice. (crucial.com)

Notes tied to the thread: was right to expect timings to degrade to the slower module; and were right that channel behavior matters — the extra 8GB usually works, but verify channel mapping and stability as above.

Recommended Answers

All 7 Replies

Member Avatar for Shinedevil

i don't exactly know, I've been looking into this but can't tell for sure that your motherboard will even function if you put in 2x4GB ram sticks in one channel, and an 8GB ram stick in the other. But, by default, your ram will switch the the highest CAS latency timings "10-10-10-27" and speed "ie. 1833Mhz". That wouldn't cause issues by itself, but, the odd channel layout that you have might. So it might be best to just go with a 2x8GB set and replace your old 2x4GB ram set, just to be on the safe side.

Member Avatar for rubberman

Most motherboards these days are dual channel boards, often requiring that you install RAM in sets of 2. My advice is to visit the vendor/manufacturer's web site and see what the specs are for this board. Anything else is a SWAG and will probably leave you with either a non-functional system, or toasty ram. Bear in mind that RAM that has been installed in a system usually cannot be returned for exchange or refund...

Member Avatar for Xyzyxx

Actually, most new motherboards these days are triple or quad channel :)

Dual channel boards don't REQUIRE you to install RAM in pairs, and triple channel boards similarly don't require you to install in three's, and it should still work if you don't. However, the dual or triple channel feature of the board will be disabled then.

Member Avatar for sgunnery

So adding 16GB (2 x8GB) should technically work then??

Member Avatar for rubberman

Xyzyxx makes a good point. Some systems do require SIMMs in pairs, but many don't. Again, read the manufacturer's specs. In any case assuming the board supports 8GB sticks, then 2x8GB should work nicely. My board supports 8 sticks, but limits them to 4GB each, with a maximum capacity of 32GB.

Member Avatar for AlexArtAndros

BIOS !!! You need new version BIOS on main board!

Member Avatar for sheikhali449

BIOS versions have many types if that is your problem then you need to know your system specs

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.