Question New RAM installed, computer starts, nothing shows on screen

Mar 6, 2019
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Purchased RAM upgrade for OptiPlex 780. Im no computer guy, so I called a buddy who is, said to leave old RAM in and just plug in new RAM. Did that and computer started but nothing on screen. For shits and giggles I switched the positioning of the RAM and nothing happened also. He then had me remove the old RAM and put new RAM into the slots where old RAM was, nothing happened. I switched back to old RAM and computer fires up and works ( how I am able to write to you ). Any suggestions I can try? Thanks


 
Mar 6, 2019
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New RAM is the crucial sticks. Other than whats on the sticker shown in photos, not sure where else to get info from.
 
Mar 6, 2019
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Thanks David. So Im guessing with this photo below, I have the old system which I cant run the new RAM ( clicking on phot is better for legibility ).

 

DavidM012

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4x 2gb ddr 3 10600 dimms will work on it.

Or 2 more of the same elpida dimms

just don't mix and match the dimms

the crucial dimms are 12800 and won't work on it.
 
Mar 6, 2019
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4x 2gb ddr 3 10600 dimms will work on it.

Or 2 more of the same elpida dimms

just don't mix and match the dimms

the crucial dimms are 12800 and won't work on it.
Oh ok, I follow... so 8gb is fine, just not the ones I have. I need ones with the 10600. Thanks man!!
 
Mar 6, 2019
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Just curious, why is it when I go to Crucial's web site and I have them scan to see whats compatible for my comp, it lists the exact RAM sticks I have now that I am having issues with?
 

DavidM012

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Must be a mistake since the core 2 & quad series only supports ddr 3 1333, otherwise known as 10600s dimms tops and in most cases only DDR 2. The Elpida dimms are DDR2 and a bit slower by the way and won't work together with the DDR 3 dimms, even the ebay seller described them wrongly as DDR 3. Both are 240 pin dimms.

You can see if the crucial dimms work as a pair as you should be able to run them underclocked at 10600 rather than 12800 but if nothing's doing it's probably incompatibility as g-skill support says those old boards probably aren't universally compatible with every brand so you have a tricky problem there, either you keep trying a variety of dimms that should work with it or go with their suggestion, the difference between the patriot set and the gskill set is $10 but at least you heard it from a reputable manufacturer and at least they are coming from their stock rather than second hand that has all been probably scavenged and mixed together.

The manual says mismatched dimms are an issue for the OptiPlex so the only way to be sure you have two pairs the same tested from the factory is to get it from gskill. If you take the chance to save $10 and get the patriots that should be compatible as well, er um, well I guess that would be a bit of a false economy if it turned out they have problems.

The selller says they are tested in memtest86 but it doesn't prove that they are guaranteed to work on the Optiplex it's probably nothing and being overly fussy but I do remember the days when the proprietary PC's had their own sets of problems and it was always difficult and expensive to get the right hardware for them.

Any DDR 3 should in principle work with it but generally speaking it's best to get stuff that was manufactured around the same year 2010 or so the newer stuff probably has a lot of modifications from the original spec as the guy says.

Interestingly some of their customers were saying they could in some cases get 16gb to work in this convo after updating the bios to v a15. However it is a rocky road and they didn't all succeed. The bios update procedure I don't know if dell have provided a utility or if the file has to be in C:\ root so the system can pick it up. Probably instructions somewhere. Might have to use freedos to get the bios updated.

If you simply buy 4x2gb you probably won't have that hassle one of the guys got 4x 2gb TwinMos dimms but I don't see any outlets selling them and the others a rabbiting about getting mismatched dimms to work however there are different models of the 780 there is a 780s and who knows how many other varieties.

The manual for the 780 I read straight from dell says it supports 4x2gb dimms only the 780s supports up to 4gb dimms that are 10600 and they seemed to be having the most problems getting 4gb dimms to work.

That there are limits to the size of modules you can install on it says it all really it was all about the time when ddr3 was a new release. There was a phase of trying to increase the amount of memory that the pc could use so they probably went through several revisions. Now ddr 4 is going through the same process chucking out endless variations and revisions from all sources and compatibility is a stumbling block. You can't try before you buy, unless you know someone with an archive of ddr 3 dimms.

What will definitely work is 2 more of the Elpida ddr 2 dimms. Trying to push the capacity with 4x2gb ddr 3 10600 dimms might mean trial and error with several different brands and trying to get 4gb dimms to work with it probably didn't happen on the orignal 780 but did on the revisions like the 780s. They used different proprietary mobo's for each model.
 
Mar 6, 2019
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See now Im confused again. Because with what you are saying makes sense between the manual and the DDR2, but I called Crucial today to ask whats up, and what they told me was the it looked as if my unit could run that 8gb DDR3 1600, it would ( think he said down clock ) to what my computer could process and that the reason why the new sticks I had weren't working was because they were single volt at 1.5 and I needed the dual volt 1.3 and 1.5. and the part number he gave me was exact as my sticks with the exception of 1 letter being different. He also said he guaranteed the new number to work correctly ( of course that's the sales pitch ).

I have a couple of older desktops here, I think I may take apart and see whats in them. If nothing, then Ill head back over to the repair shop and see if they can test different sticks to see whats gonna work. Buying returning trial and error could take a bit of time.

I appreciate all the help you've given David. If youre interested in knowing what I find out, Ill post up what the end results are when I figure it all out.
 

DavidM012

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The core duo and quad series simply doesn't run ddr3 1600 only ddr 3 1333 there is no way a proprietary 775 mobo from dell would be able to run it. The board would only support the max the cpu allows.

They made a mistake and are trying to blind you with science? All good fun! That it may run downclocked it might if it wasn't a dell but dell is proprietary they made the board in house to their own specs. not the general specs you'd normally find on most atx boards of that era. Memory density could be the exact issue as your g skill guy said.

Since memory probably depends on some microcode in the mobo bios probably similar to the cpu microcode to detect cpu it probably won't recognize anything later than it's release and pc3 12800/ddr3 1600 is later than pc3/ddr 3 1333.

How would it know to downclock a 12800 dimm? Or decide it could run 1.3v rather than 1.5v? There would have to be a logic circuit to determine that somewhere.

Also the 780 manual strictly specifies a 2gb limit, what logic would it have to say, oh this is a 4gb dimm and I can only use 2gb so I'll only use half of it? Doesn't exist. It won't recognize the dimm. and matched pairs of dimms to prevent any drop in performance. so mismatched dimms might work in some cases but not at full speed, that's the rules I understood from the book.

Everyone in the previous convo was having difficulty with 4gb with the 780 and one guy said he got 2x4gb dimms to run after he updated the bios to a15 that are 1.5v.

The problem in updating the bios is you'd need to load it from DOS and since the floppy disk retired there's no convenient way to exactly do that any more. Oh well the bios page says it does boot off a DOS usb drive you can make one using rufus. Windows 10 retired the boot to dos cmd prompt.

However his version was the 780, he didn't specify if was a 780 MT so probably it's a different mobo and the 2gb limit doesn't apply. The bios has to decide something like if not this then that and it's programmed in at the factory and the specs will fixed to what they decided at the time.

Or well someone's getting mixed up here as I found 2 data sheets one says the 780 has the ddr3 10600 1333 fsb and the other says the 780 MT has the ddr 2 1066 fsb. That means it has the 2 ddr2 dimms as standard but the manual says it could run the ddr 3 1333/ pc3 10600 in 4x2gb layout.

e7600 version with 1066fsb (the 2x2 ddr 2 dimms)

8400 version with 1333fsb (that should support 4gb dimms?)

There are two models with the same model number with the core 2 due 8400 version saying installed ram size 4gb and the e7600 version saying installed ram size 2gb.

And there are two 780 manuals with different titles that I downloaded... one says 780 tech guide book and one says 780 service manual. The 780 service manual says, 4gb limit, the 780 tech guidebook says 2gb limit.

So we have to do a bit more work to identify which 780 you have exactly. They are both mid towers the only thing I can find on the cnet site is a model number 468-9822 for the duo 8400 version and model number that I'm starting to think shouldn't have the 2gb limit when the bios is updated.

Going with the proprietary board theory though

The socket is oriented 45 degrees compared to most other 775 boards

It is different somehow in some way probably right down to every component they used in manufacturing. Somewhere in there is a logic that says 'I don't like dimms'.

So, my conclusion is that based on the spotty info where the last guy says

https://www.crucial.com/usa/en/ct51264bd160b

worked in 4x4gb config

he bought the pc from ebay around 2016 second hand but doesn't say what version of the bios was installed. And that he tried 4 different brands of memory, and the first guy said he tried 3 different brands none of which worked.

What his definition of working no problem is, couldn't say. It wasn't running at pc3 12800 and there's no way to know if it was even running at pc3 10600. Maybe the system down clocked it to 600mhz or something. How would we know? It could see 16gb but at what speed? and something was timing out the display driver?

The story goes along the lines of people maybe trying to upgrade the memory with or without the bios update and having compatibility problems either way. And someone in the middle also chucks in the idea of the 2gb limit.

And there is a third 780 optiplex manual saying 4gb limit with the title tech guide same as the 2gb limit version. Something happened way back when. Dell.

So the gist of it was the 4gb modules giving them grief anyway. They seemed to be keep trying 12800 dimms when the cpu only supports 10600 dimms max anyway so maybe ultimately with the a15 bios update there isn't any actual problem with 4gb 10600 dimms after all.
 
Reactions: BringerOfTea
Mar 6, 2019
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David, well I thank you. I read somewhere about doing a BIOS update ( Ive never done one, never knew one was needed ), so I googled it yesterday and thru Dell they offered it. Latest version is A15, which is good that I updated because I was at A1. With all that you wrote explaining things in your last post, I came across something you wrote: "one guy said he got 2x4gb dimms to run after he updated the bios to a15" got me thinking. I never tried to check the sticks after the update, only prior.

Luckily, the mail guy hadn't shown up yet, ran out to the box and grabbed them. Took out both old sticks, and dropped in 1 of the Crucial sticks... When I plugged in computer, it didn't autostart, I got excited. I hit the power button and the computer came to life. Loaded just fine. I was like oh shit.... I pulled it back out and said ok, here goes stick #2. snapped into place, hooked it up, computer didn't autostart. Got more excited. I hit the power button, heard 2 little beeps, and my computer started to do its thing. Got a message on screen saying new memory was detected blah blah blah. I ran a memory test and everything passed.

Computer is currently running great! Programs are loading faster :)

Thanks again for all your input and research on the matter.

 

DavidM012

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I made a couple of mistakes on the way the elpida is ddr3 not ddr2 but I wasn't sure if pc3 8500u or 1066 isn't pc3 10600 so it was confusing

1066 is 533mhz ddr3 8500 (1066 data rate)

10600 is 666mhz ddr3 10600. (1333 data rate)

12800 is 800mhz ddr3 12800 (1600 data rate)

sometimes they refer to the data rate rather than the module name. anyway yes I should have emphasized the bios update more strongly instead of waffling about ddr 3, but as they were stressing that they tried about 7 different types of 4gb ddr3 12800 dimms I thought it was some compatibility problem and 3 manuals one with the 2gb limit was also confusing but, if the crucial 12800's or ddr3 1600's are running downclocked to pc3 10600 or ddr3 1333, then you got one the 12800 modules that it gets on with.

The guys with the a1 bios couldn't even get 4gb 10600/1333 dimms to work on it. There is a 2gb limit on the a1 bios.

Somewhere along the way they started probably releasing 780's with the a15 bios at some point so some were having problems and some weren't anyway with all that flailing about, got there in the end.

You can see what speed it's running at with cpu-z on the memory tab should say 666.67mhz, since the cpu only supports 10600 is 666mhz ddr3 10600. (1333 data rate) it's 666.67 x2 to get 1333 because ddr stands for double date rate. That is faster than the ddr3 8500 which is 533mhz x 2.
 

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