Found a couple of riser installation videos for the T5500 when looking for the T7500.  Not sure how similar they are or if they'll give any ideas.  precision t7500 riser board installation youtube

Service Manual has RAM matrix, so I attached it.  Don't know if you have it already.

Test or replace the 3v size 2032 battery in case that's giving issues, especially if it's 5+ years old.  Bad batteries affect BIOS and therefore PC operation.

@bradthetechnut​ 

Thanks Brad for your replys.

I replaced the battery not long ago, so it should be good.

I'll check out the info in your first post and see how I go.

Bill

Have you checked if both cpu are SLBVX as stepping ? ( because there's also an ES variant )

@mazzinia_​  Thanks

You will need to explain further as I don't know what this means. I have tested both individually and they work. They were sold as a matched pair.

Hi @mazzinia_ 

Where does one find stepping for their CPU?

Hello,

I'm wondering if you alredy found a solution for the issue.

I'm in the same problem.

Purchased a T7500 with dual E5620 and wanted to replace with dual X5675

I get your same fault with the second tray inserted.

I've tested both processors on the motherboard socket and they are perfectly working in  single configuration. 

Tested many memory modules and configurations. 

Upgraded BIOS to the latest A17 version.

As I got back to DUAL E5620 everything works fine, with both processors. 

So I'm stuck. CPU are both good, all memory modules are good. The second processor tray works.

But as I put the six core X5675 I have yor same behavior.

Perhaps exist an updated 2nd processor adapter and the one I have is an earlier model-not compatible with the 6 core Xeons? I'm just guessing.

I really don't know what to do.

What specific error does it give you - RAM error?  Precision T3500/T5500/T7500 Workstations Diagnostic Lights and Beep Codes

Thread that may be worth a read:  Dell precision t7500 dual processor compatibility

Folks, still no success with getting my T7500 PC to function with the 2nd CPU installed. Fails to reach POST. Power light orange, lights 2, 3 & 4 solid green, fans at about 100%.

Is it possible that there is something that needs to be changed in Set-up?

I have tried everything that has been suggested this and other threads.

Well, it would help trying a different riser board for the 2nd cpu (maybe the other one is defective).

Or the connector for the riser board ( on the mb ) has some issue. Just some ideas

That was my conclusion also so I have purchased another riser, I'll see how that goes when it arrives in a couple of weeks.

Thanks

Update on "progress", getting closer, still no cigar!

Firstly, thank you to those folks who have offered suggestions to help solve this issue, much appreciated.

I purchased a new riser board and on first installation the PC booted normally, success!? Seems that after months of messing about with the first riser it was faulty. But although it is using all 48GB of memory (24GB on the mb & 24GB on the riser) it is still only using the 6 cores, 12 threads of the primary CPU!! Both CPUs are fully functional, as I have had each on the mb. BIOS sees both CPUs but Taskmanager and CPUID & IPM see only the primary CPU. CPUID limit in BIOS is set to zero. BIOS is the latest version I can find, A18. I also tried to find a newer version of the 5520 chipset (currently A07?). Advanced Settings in msconfig shows 0-12 but is this cores or threads? Selecting either 0 or 12 does not work.

It has been suggested to me that trying a Windows11 install might work (with resgistry key changes to overcome the issues with hardware compatibitily). I am also wondering if a Windows10 reinstall might also work.

Any further help will most appreciated.

Which version of windows 10 are you using ? Asking because Home edition is limited to 1 cpu

Yep, I have the Home version! Arrrggghh !!!

Thanks that explains all.