Dell T7820: CPU Upgrade Issues *Solved*

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Quick Read: Did you buy a used barebones Dell T7820 or upgrade your CPU from Xeon Silver to Gold and now the T7820 won’t boot? Are you getting the error Code Memory/RAM failure: 2 amber blinks followed by a short pause, 4 white blinks, long pause, then repeats:?

Solution: Ensure your BIOS is at least 2.6.3 or later.

More Details:

I recently purchased 3 used Dell Precision Workstations model T7820 from eBay. They will be the replacements for my next generation Home Lab with vSphere 8. These used T7820 are barebone systems that didn’t come with a CPU or RAM. Other than a vNivida Video card they were pretty much empty. After inserting a Xeon 6252 and RAM modules, they all powered on but only one would post. The other two simply gave me a blink code (2 amber blinks followed by a short pause, 4 white blinks, long pause, then repeats). It was an odd error as their manuals stated it supported the Xeon Gold 6252 and 2933Mhz RAM.

Looking at the Dell 7820 manual I soon found Dell code description that matched the blink code: Memory/RAM failure. I swapped the known working RAM and CPU between the systems but still the errors persisted. So at this point, I knew my RAM and CPU were compatible with the T7820 but why would only 1 of 3 them work?

I now put a focus on the one system that worked. I first checked its BIOS level. It was running Dell BIOS 2.6.3 and funny enough the BIOS release notes specifically called out fixing a memory speed issue. It read: ‘Supports memory speed of 2933 MHz with two memory modules per channel’

It appears that when the T7820 posts, it queries the CPU for its max memory speed rating. In my case the Xeon 6252 has a max memory speed is 2933Mhz. So, even if I put in 2666Mhz RAM it still will not work, because its asking the CPU for is max speed rating. Dell BIOS 2.6.3 fixes this issue allowing the for faster memory speeds to be supported.

Knowing this, the fix should be simple. All I need to do is update my BIOS to 2.6.3 or later. However, the issue is I can’t update or even check the BIOS version on my 2 non-working systems. To do this I’m going to need a Xeon CPU whose max RAM frequency is slower than 2933Mhz, it’s something I don’t have. Enter my eBay Seller oztech llc. to the rescue!

I’ve heard of so many bad experiences when working with eBay sellers, but working with the eBay vendor oztech llc has been an absolute pleasure and I would highly recommend them. They are very responsive, helpful, and knowledgeable around the product they sell. They had not heard of this issue before but were willing to help and after a short call explaining my issue, they promptly shipped out a Xeon Silver 4114 CPU that supported a max RAM speed of 2666Mhz and matching RAM. This should allow me power on my T7820s and update to the latest Dell BIOS (2.29.0)

When the Xeon Silver CPU arrived I did the following:

  • Prepare the T7820
    • Removed the existing Xeon Gold CPU and 2933 Mhz RAM
    • Plugged in the power to the system and then unplugged (don’t skip this step)
    • Cleared the CMOS
    • Installed the Xeon Silver CPU and 2666Mhz RAM in Slot one
    • Plugged in the T7820
    • It power cycled about 4 times as it adjusted the system settings, and then it booted!
  • Confirm Current BIOS Level
    • During boot I pushed F12 and went into setup
    • Confirmed its BIOS level to be 1.7.1
  • Updating the BIOS to 2.29.0
    • The T7820 BIOS update is designed to work with Windows 10.
    • I booted to Windows 10, and ran the 2.29.0 BIOS update
    • The update confirmed it was currently at 1.7.1
    • I ran the BIOS update
    • Once it was completed I checked the T7820 BIOS but it came up with BIOS 2.6.3
    • I ran the BIOS update again, it confirmed 2.6.3 was current and it would update the T7820 to 2.29.0
    • After a reboot I confirmed the BIOS to be 2.29.0
  • Finally, installing the Xeon Gold CPU
    • Powered down the T7820, removed the Xeon Silver CPU and RAM
    • Plugged in the power then removed, and cleared the CMOS
    • Inserted the Xeon Gold CPU / 2933Mhz RAM, powered on, and allowed it to adjust for the new components (reboots multiple)
    • Went into setup and confirmed it saw the Xeon Gold CPU
  • I repeated this process on my other T7820, only its BIOS was 1.4.1.
  • I had no issues with either system after I completed this process.

Why this odd BIOS Update behavior? Though I could not find any information in the 2.29.0 release notes, I can only assume that it had a requirement for systems to be on 2.6.3 to be able to update. This would explain why it updated the system to 2.6.3 first then it updated to 2.29.0

It took a bit of trial and error to figure out this issue but with the great help of oztech and their all out willingness to ensure my satisfaction I now have 3 working T7820s. Next I’m off to install ESXi 8 and update my Home Lab but that my readers will be a different blog post.

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