Simple Processor / Memory Support Question

DeaconFrost

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I'm trying to piece together a new home EXSi box using a Precision T5810 tower I bought online. I picked this model because I have a pile of 16 GB DDR4 ECC RDIMMs that I know are compatible with the tower. I tested them in a tower I have in the office. I bought a Xeon E5-2640v3 CPU. I populated the first two of eight memory slots, booted up, saw 32 GB. Powered down, populated all slots, and got an error. Amber blink code 2,7 which refers to a memory power error. The manual suggests the usual, remove all sticks but two, power on, add them back, etc to find out what sticks are bad. To make a long store short, I can boot fine with the first 4 memory slots fill, seeing 64 GB of memory. I can't boot once I go beyond the first four slots. I've rotated and swapped out the memory several times over, and I can always reproduce the error if I go beyond the first 4 slots.

So, that being said, Intel site lists the processor supporting 4 memory channels. Does this equate to memory slots? As in, if I wanted to populate all 8 slots, I'd need a higher end processor? I didn't think so, but I'm stuck on the fact I can't fill more than 4 slots. The system BIOS is up to date. I thought about trying to reset the CMOS and trying again, but wanted to check here first. I have little experience building systems using Xeon processors and anything more than 4 memory slots.
 

kirbyrj

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No, 4 memory channels doesn't refer to 4 memory slots.

Did you test all of the memory individually? Do all 8 sticks work when you run them say 2 at a time?
 

DeaconFrost

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I've got 24 sticks and was rotating them in and out. Regardless of which sticks I use, I can't boot with more than the first 4 populated.
 

DeaconFrost

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According to the seller, it was extensively tested. Their suggestion was to reseat the processor and make sure there's no debris or anything on the underside of the CPU, given that it contains the memory controller. I'll try that ASAP.
 

DeaconFrost

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It's at the latest BIOS, and I tried clearing the CMOS this morning. I reseated the processor, too. I threw Windows 10 on it for testing, and it seems very stable using 16x4, so I may just leave it as is. I'm planning this to run ESXi, so 16 threads and 64 GB of memory should give me plenty to work with.
 
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I've experienced once or twice before over the years that if you push too hard on the RAM you can break a trace or solder joint, especially in a case that gives. It's surprisingly easy to do on server motherboards too... Not saying you did that, but it's food for thought. During shipping the board could've flexed.

Could be junk in the slots, I've seen chunks of packing peanuts in memory slots before. It could need additional voltage or relaxed settings on the RAM to run that many sticks. Dirty CPU pads, although I very much doubt that because the pins usually dent LGA pads. A CPU with some fried channels. I'm just spit balling potential ideas.
 

DeaconFrost

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It may have something to do with double sided or single sided as well.
Thanks for this suggestion. I'm going to do some research into the memory I have. It runs very stable with 64 GB, so it's still a very usable home ESXi setup. I swapped out many DIMMS and used compressed air to make sure the slot is clear. I reseated the processor and made sure that was clean as well as the socket. I can't rule out the CPU, so in time, I may try another one to to see.
 

SamirD

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I've run across sockets being picky like this before too. But it doesn't sound right that the second bank of 4 aren't working. It does sound like a cpu/motherboard issue. Do you have a spare cpu to swap out and check? If the problem still persists with a different cpu, I would say it's a motherboard issue.
 

Dan_D

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If you have eight slots you shouldn't be populating the first four. Whatever that means. You should be using two modules in each bank.
 

DeaconFrost

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I have the four slots fill in the method recommended by the manual, and it works perfectly fine with four sticks installed. They are in corresponding banks. My issue is trying to use all eight slots with identical memory sticks.
 
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