I believe the answer should be A, the power supply is not providing enough power. This is a crap comptia question. Testing the Power consumption of a system by varying the number of DDR 4 RAM Modules 16x 8GB - 232W 4x 8GB - 205W Savings: 27W https://www.servethehome.com/ddr4-dimms-system-power-consumption-tested/ - DDR3 RAM uses a 240-pin connector, while DDR4 RAM uses a 288-pin connector. - The standard voltage of DDR3 RAM sits at 1.5V, while DDR3L RAM can use both 1.35V and 1.5V. DDR4 RAM, on the other hand, uses 1.2V. Low Standard Performance DDR3 1.35 V 1.50 V 1.65 V DDR4 1.05 V 1.20 V 1.35 V - You cannot install a DDR4 RAM onto a DDR3 port or vice versa! - While speaking in general terms, and motherboard built between the years 2007 and 2014 is likely to support DDR3 RAM, while models made after 2014 are more likely to support the DDR4 module https://beebom.com/ddr3-vs-ddr4-ram/

You can't put 2 type of mem stick in the system. since they are difference pin DDR3 stick can't physically fit into a DDR4 slot and vice versa so D is an incorrect answer

How can you mix DDR3 and DDR4 memories in one motherboard?

I believe the answer is A. This was on one of the practice exam dumps we had but the wording was a bit different but basically 256GB of memory if all 4 sticks were able to be read but only half 128GB is being seen so power to the rest of the RAMs must be the issue as I don't see what DDR4 and DDR3 have to do with the server not being able to pick up all 256GB

So um.... After re-reading.... and re-re-reading the question. The only answer that make sense is D. As the question asks "Which of the following will "-> not <-" allow the server to recognize all of the memory installed at the same time?" The question is horrible and they seem to want you to miss that word, which is why so many people can't agree on the answer as the other 3 could help.

Correct Answer is D. just know that DDR3 supports 128gb max memory and that the Server NEEDS DDR4 not that it HAS or can support DDR4.

this questions and answer doesn't make ANY sense!!!

This question clearly states a number of things that you need to consider. 1: The user guide for the machine says it CAN support 8 32gb sticks. 2: ALL of the memory modules ARE working, but only half of them are detected when they are all installed together. 3: With all the ram installed, the system boots fine, but the BIOS does not detect the added ram. -From these facts we MUST rule out D as a valid option. -No statement in the question implies that the system will not run, or is locking up, so option C is also not valid. -ECC errors happen as the memory is used, and would not prevent it from being detected in the BIOS, so option B is not valid. -Too much power draw would prevent the system from booting, or it would lock it up. It can not selectively choose Not to power a few sticks of ram if the power supply was inadequate. As such we must assume that this question was recorded and published incorrectly.

DDR3 & DDR4 memory needs to be installed? The question says the tech upgraded from 2 8Gbp to 8 32Gbp sticks and doesn't mention what kind of memory he or she used. So why would I assume that the tech is using ECC memory? Or, any otherwise?

I think you’re all reading it wrong it doesn’t say anything about sharing DDR3 and DDR4 in answer D. It says the server needs DDR4 and DDR3 is installed , meaning you need to replace DDR3 with DRR4

I think we all agree D is totally wrong, but what is Comptia looking for on the exam?

Can I use DDR3 and DDR4 RAMS together? First of all, DDR3 and DDR4 are physically different, so if DDR3 fits in your motherboard, DDR4 won’t, and vice versa. The short answer here is no, you cannot do that. Even if you somehow manage to install both types of RAM, your processor will only support one of them, and the other will either cause you to not be able to boot, or it would just sit there and do nothing(most likely the first). https://www.quora.com/Can-I-use-DDR3-and-DDR4-RAMS-together#:~:text=No%2C%20you%20can't.,as%20they%20have%20different%20pins.

CompTIA is completely wrong, the answer is A. Not only does DDR3 have completely different number of pins, you cant fit DDR3 into DDR4 slots and vice versa. I would think the people who make the questions should know this. I mean they have actual IT technicians making the questions right?

B seems to be the only answer that makes sense. TIHNK WELL AND READ UP ON ECC

I might be in the wrong but i dont think its A since powering ram does not require much power, so if we push that idea to the side for a bit, I looked up some server motherboards that support DDR3 only rams and saw in the specification list that it: Up to 128GB DDR3 ECC/non-ECC UDIMM. https://www.supermicro.com/products/motherboard/Xeon/C600/X9DRH-7F.cfm In addition, DDR4 server motherboards are able to handle 1TB of RAM. Honestly, still conflicted between the two answers but this was one of my thought process when doing this question

MeasureUp has this exact question and answers listed, but lists POWER as the correct answer

Can't you have two SETS of different memory modules on a single motherboard? Ex: Two DDR3 Slots and Two DD4 Slots, on the same MB. If so, then Answer D would make sense. Because if you were to put them all in at once, even if put in the correct slots (which, physically, you have no other option but to do so), then it won't fully be read. You'd have to put the DDR4 memory in first (or DD3), and then the other. That's my guess. I could be wrong. Would like an explanation.