This question is similar to Computer won't start with RAM in certain slots, but isn't about sticking in certain specific RAM slots, but rather the number of RAM modules.

I have a Lenovo ThinkServer TS140 (Intel Xeon configuration). The system originally came with 4 GB ECC RAM, which I upgraded to 12 GB immediately after I bought the machine. However, this became too low later on in the computer's life, and so I purchased another 8 GB ECC RAM module.

My original plan was to convert the system to run on 20 GB of memory, using all three of the modules I had thus far. However, as soon as I inserted the third module, the computer refused to POST and made repeated beeping sounds through the PC speaker.

As per the service manual of the machine, RAM has to be loaded in slots 2, 4, 1, then 3 in that order. The two existing modules were loaded with the original 4 GB one in slot 2 and the later 8 GB one in slot 4. I inserted the newly acquired one into slot 1, and that caused the issue. I also tried rearranging the modules in different ways using slots 2, 4, and 1, but the computer still refused to boot and beeped at me.

In the end, I resolved the issue by removing the 4 GB module entirely and making do with 16 GB RAM.

Why is my computer refusing to boot when I try to use three RAM modules? Nowhere is it mentioned in the service manual that this configuration is unsupported.

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  • Funnily enough, I have a TS140 running in the exact same way. Two 8GB sticks and the original single 4. Are they mismatched in any way? – Sam Forbis Feb 28 at 13:08
  • @SamForbis I read it as they are using 3x4GB and 1x8GB so it seems they aren't doing it in pairs. – UnhandledExcepSean Feb 28 at 14:31

I have a TS140 as well. It came with the 4GB module like yours did, and that was nowhere near what I wanted. The only difference being that I purchased my two 8GB sticks together, meaning they are identical. I also bought ones that matched the original 4GB stick's frequency. Maybe your service manual doesn't say anything about it, but I was able to find this easy-to-miss blurb from the online manual:

Note: The installed memory modules must be the same type with the same voltage and frequency.

I suspect that either the new module has some sort of mismatch or you may need to rearrange the modules so that the two 8GB sticks are on the same channel. If your board is similar to mine, you'll have green and blue colored slots. Try putting the 8GB modules in one color slot and the 4GB stick in the other.

This is not an ideal setup (although I am successfully running it in my TS140), as you would ideally have all (4) matching modules. It would be interesting to see the specs on each of your modules to see if they are rated for different voltages, timings, or frequencies.

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Some motherboards require matched RAM modules in pairs only. Sometimes they have to be placed in particular order by size (if allowed). Check your manual.

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  • As I said in the question, other than the loading order of 2, 4, 1, 3, there are no other restrictions on loading RAM mentioned in my service manual. – gparyani Feb 27 at 19:41

The manual for that machine states 16Gb max ram with 4Gb modules. Since 8Gb modules are unsupported, anything may happen if you install one

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  • Link to the manual you're looking at? I saw no such restriction in the manual that came with my machine (on CD). – gparyani Feb 28 at 10:58
  • check page 41 towards the bottom. All boards have a list of acceptable sizes, ranks and speeds, you cant just install something that isn't listed. – camelccc Feb 28 at 11:20
  • There is a discrepancy with this manual, check the manual I linked in my answer. It says it supports 32GB. I know that at least SOME TS140's support more than 16GB because mine is running successfully with 20. – Sam Forbis Feb 28 at 14:55
  • hmm. this is a different version of the manual to the one I looked at, that states 4gb modules supported in any number, and max is 32Gb with 4x8Gb modules. It says nothing about mixing sizes, othet than restrictions on 2Gb modules. As clear as mud to me – camelccc Feb 28 at 15:42
  • It seems your manual is for an older version of the computer. The one that came with mine specifies that 32 GB are supported. – gparyani Feb 28 at 19:25

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