Dell Precision 690 upgraded to Precision T7400 Motherboard


Well, I did it!
Took less than 2 hours in the end.
Excuse shoddy photos, almost didn’t take any but remembered how hard it was to find good data so took pity on everyone else.

What you will need:

Long reach crosshead screwdriver.
Hacksaw with bimetal blade.
Bastard file.
Magnet on a stick type thing. If you don’t have one just shred an old HDD and mount the curved magnet to a stick with cable ties or glue.
Good lighting.
Clear flat work surface.
Even though I have a decent workshop I found the bed to be best, good natural light and decent working height. And no solder splats or metal shavings.

Tools and Cards

^^^ Crappy DIY tools but decent bi-metal hacksaw blade ^^^

Xeon X54xx or X52xx CPU(s) + heatsinks from the 690 or a Mac Pro
RAM from your 690
RW199 Precision T7400 motherboard
MM776 T7400 front IO panel. FF219 is just the metal case
WY005 T7400 front IO panel ribbon cable
HX637 T7400 front audio cable (optional if you have a proper soundcard)


Riser 1 +2 0JF806 (0G9460 + Riser Riser 2 0H9376)
Riser 3 + 4 0JF807 (0M9008 + Riser Riser 4 0JF807)

690 MoBo

^^^ Precision 690 Motherboard ^^^

T7400 MoBo

^^^ Precision T7400 Motherboard ^^^

Notes on parts:

There are a lot of common parts. Air ducting, RAM risers, heatsinks, cables, RAM, PSU, case parts – most of it really. The front panel + cable and CPUs + motherboard are the main differences.
You will need the front panel and its ribbon cable.
T7400 and 690 versions are different although they look the same. There are auction listings for front panels that say they’re for both but its a nomenclature fail on their part. FF219 is common between them but its just the metal shell. The boards are different. The ribbon cables are very similar but have different key pins.
If you felt brave you could drill out the blank one but you’d have to connect to it too. Better to buy one, got my cable for £3 inc P&P, front panel for £7.50 inc P&P.
The ribbon cable is not 0.1″ pitch like an IDE cable, its 2mm or smaller pitch. Just in case you’d thought to use an old IDE cable.

690 Front Panel^^^ Precision 690 Front Panel ^^^

Behind Front Panel^^^ Precision T7400 Front Panel ^^^
PSU cables fit both motherboards fine.
Pro tip: take TONS of photos at every stage for reference.
Stripped out all cards and drives, bent all cables etc out of the way.

Case Cables
Disconnected all PSU cables, fan connectors, intrusion switch, front panel Firewire and the front panel ribbon cable.
Removed front dual fan assembly (2 screws).
Removed CPU/RAM air guide, heatsinks, RAM risers if fitted, RAM fan and support frame.
Removed screws holding motherboard frame in position (at rear by IO ports).
Slid motherboard tray out.
Unscrewed front IO panel (3 screws).
Unplugged Firewire and ribbon cable at front panel end.
Leave Firewire cable in place where it passes under motherboard.
Remove the ribbon cable, noting its route.
Beware when unplugging the ribbon cable for the IO panel, it has little teeth that hold it in and in mine they had become brittle with age or heat. They broke even with gentle leverage with a flat bladed screwdriver.

Clean EVERYTHING! Surprised at how little dust there was, but its best out of the way. For static reasons don’t do it till all active devices are removed; drives, cards, motherboard etc. PSU is OK.

MoBo IO Port Lineup

Stacked motherboards together to see the difference at rear.
Most IO ports line up, but a cluster in the middle don’t.

MoBo Slot Lineup

Card slots line up fine.
Took me a few minutes with a decent hacksaw blade and some files to make it right. Use a magnet in a bag to get the metal chips then hoover the case very thoroughly. The thought of what a steel filing might do stuck in a slot or between some pins on the motherboard made me do a good job.

690 Case Rear Hackery

T7400 PS2 Port Alignment

Feed the T7400 front panel IO ribbon cable through the slots in the case under the motherboard area.
Fit the T7400 front IO panel. You will find that only the 2 side screws will fit, the centre one is offset by about 1/4″. I couldn’t be arsed to remove everything in order to drill and tap a new hole, the IO panel is held fine with 2 screws and the power switch works so I left it.

When fitting the T7400 motherboard tray be sure to make certain you have engaged all the tabs in the case, you need about 5 hands to apply pressure in all the right places.
Use a couple of screws in the front fan assembly’s holes to hold the motherboard & tray in position while you upend the case to screw it in place from the rear (2 screws).

Motherboard wiring:
Plug in the front Firewire cable first, then intrusion switch, then the front panel IO ribbon cable.
Then HDD fan(s), power, then dual front fan block (remember to remove the temp screws first).
Replace SATA cables and cards, then drives, then done!

Getting there

Complete sans RAM Risers

My experiences afterwards:
T7400 BIOS was A01 when I got it, now A11.
Annoyingly you lose a PCI-e slot in the upgrade, its a more modern machine so why swap a useful 8x PCI-e for another PCI-X? You also lose the IDE port that the 690 DVD burner used.
The second GPU card slot won’t accept a RAID card or any non-GPU card, at least not so far. There may be an nVidia SLI chip mediating between the 16x slots that won’t work unless it finds some magic string in the GPU boot ROM or something horrid like that.
In the 690 I had a Revodrive 240Gb in the first PCI-e, then nVidia GTX660 or Quadro FX 4600, then PCI-e RAID HP P400 512Mb + battery, then Soundblaster X-Fi in a PCI slot. Since replaced the X-Fi with an Audigy 2 ZS as it sounds better than the X-Fi.

1600Mhz FSB CPU with 667Mhz RAM instead of 800Mhz

Because the RAM in my 690 was 667 not 800 I was unsure if a 1600Mhz FSB Xeon X5492 would work, there is much contradictory advice out there.
I can assure you that it DOES work, just at 640Mhz rather than 667. Or so the BIOS says.
I got a cheap Xeon X5272 (dual core 3.4Ghz 6Mb cache 1600Mhz FSB) just in case it wouldn’t work. X5492s are still a bit expensive for an experiment.
I imaged the Revodrive before starting just in case, but it booted fine.

“God said 640×480. Realism is over-rated.”

TempleOS style CRT shot from later reinstall

^^^ Screen ‘shot’ from a later reinstall ^^^

Fine for TempleOS, not so much for me.
First boot was 640×480, found about 35 devices, installed drivers automagically, rebooted twice, all fine.
I’m allergic to all these registry/driver optimiser junkware programs but there is one that actually works: DriverMAX.
Used it on the 690 as well, it finds much newer drivers than windows or Google does. Its a legit program, surprisingly. I only used it because there’s a blog post somewhere by a guy upgrading his 690 to Windows 7 x64 and he reported good results.
Once you’ve used it to get all the drivers you need it can export them as a zip for later use.
You can then uninstall it.

After the T7400 upgrade I noticed that a few times a minute my audio would stutter. I put it down to crappy X-Fi drivers and change of mobo. I used DPC Latency Checker from here.
Its free and shows latency spikes. Very useful.
Sound card was a red herring, I had the Intel Matrix Storage Manager installed on the 690 and as soon as I killed its process and deinstalled it the problem went away. I replaced the X-Fi card with an Audigy 2 ZS anyway because it sounded better.
Its only a problem if you don’t do a clean OS install.

Great Success although not photographicly

^^^ Screen ‘shot’ from Windows 7 x64 Experience Index ^^^

Machine is not quite as fast as it was (Solidworks Performance Test – desktop is very snappy) but I put that down to going from 8 cores at 3ghz to 2 cores at 3.4Ghz as well as only having 1 CPU. Probably memory channel efficiency and other chipset and bus related stuff, you need to have both CPU sockets populated to get quad channel RAM. CAD is  mainly a single thread performance thing apart from raytraced rendering and some physics simulations.
When I have a pair of X5492s in there it’ll fly. (Later note: it did)
800Mhz RAM is still a bit pricey compared to 667, but I’ll gradually get that too.  (Later note: ended up with the RAM risers and 16x 2GB 800Mhz as well).

In summary its well worth doing, lots of crap info around about what’s needed and how to do it but I hope this will be the definitive practical guide. I know its a bit verbose, but it should be helpful.

Its 2013, but these machines are still fast. And absolutely stable, which means a lot for CAD, code compilation, rendering – anything iterative that runs for a good while. With a bit of careful eBay lurking you can get a 690 to a T7400 for under £50.
There are still quite a few people out there with love for these machines. I’m a Starving Hacker(tm), but even if I COULD afford some i7 quad SLI Titan monster I think I’d rather spend the money on a top end scope or tools or something.
I’m even still using a CRT monitor, but it is a 24″ widescreen @ 1920×1200.
I may get a 1440p 27″ IPS when it dies.

Most of this is from a forum post I intended to randomly drop somewhere but never finished. Better late than never I suppose? Let me know if there is anything more I need to add.

9 thoughts on “Dell Precision 690 upgraded to Precision T7400 Motherboard”

  1. Thank you sooooooo much for this, I’d been trying to figure out for the longest time if it was worth it and you’ve convinced me. I’m gonna take the plunge as soon as I have enough for both a 7870 XT and new MOBO.

    1. Go for it, you wo’t regret it. Its actually more straightforward than I made it seem. I just wanted to cover EVERYTHING I did and got; you never know what the missing piece of the puzzle is for someone else. You’ll get it done in a couple of hours at most.
      Glad the information is useful.

      1. Hello!

        I want to buy a motherboard Dell RW199 (T7400) and to assemble a budget computer in a standard case (Full Tower for E-ATX).

        I looked the photos RW199 and MM776, but I did not understand where to connect the power and reset buttons.

        Can you show me photos or video of how you did it?

        Thank you!

        1. Hi, I’m afraid these aren’t PCs in the conventional sense, they are workstations.
          They use a custom front panel PCB that has the power button, several status LEDs, USB, audio, etc that connects to the front panel via a 20(?) pin ribbon cable.
          Therefore it isn’t as easy as with a PC.
          The PCB layout is also ‘on the other side’ compared to ATX. Its more like BTX.
          That means the back panel connectors and card slots are on the wrong side.
          These systems are cheap now so I’d advise you just get a barebones system whole. It will save you a lot of annoyance.

  2. The front panel part numbers was great thanks.
    I’m installing in a nice big case but need the front panel and find the part number not so much fun.

    1. Glad it was useful. Dell part numbers are a minefield. Especially when sellers don’t understand them and use the same part number for several different and incompatible things.
      Virtually no e-Bay listings get that FF219 is just the metal case FOR the front panel, not the actual panel its own self.
      They really are lovely big cases, they would be more widely used but for their reverse BTX type motherboard mounting.
      Mass is the downside, moved recently and my machine (fully filled with RAID drives, expansion cards, 5.25″ floppy drive etc) must have weighed well north of 20kg!
      Good luck with your project.
      If theres any more help or info you need don’t hesitate to get in touch.

  3. Thank you so much for this it really helped me out! I picked up an old Precision 690 from a thrift store for 12 bucks. Decided to do this upgrade based off this write-up and Im really glad I did. I did however have a problem that wasnt listed here. I have a different, probably older version of the 690 mobo, it has old school KB/Mouse connectors next to the semi-old-school PS2 connectors. So, the I/O panel wasnt quite the same. No big deal. However, on the new Mobo RW199, the CPU slot for CPU 01 was slightly off center compared to the original 690 mobo. I was able to make some modifications to the support cage underneath CPU 01 and get the screws in for the heatsink, but it was blocked by the mobo. I took the posts on the heatsink and ground them down with a dremel tool to accomodate for the thickness of the mobo, because I didnt want to try to grind out the holes in the mobo in case there was a wire in there. Its a janky setup, but the heatsink is now effective and the system is running stable with two Xeon X3482 3.2Ghz Quad core CPU’s, 64GB DDR2 667Mhz, and a GTX 770 GPU. This is now a 12 year old PC… But in 2018 it still runs most games on high or ultra settings with reasonable frame rates! I hate that the new mobo has one fewer PCIe slots, but thats OK. I just lose USB 3.1 10g ports. I also had an old SoundBlaster X-Fi PCI card that I can use instead of the SBX. In the one available PCIe slot, I will be using a SATA III controller to eliminate the SATA II bottleneck, along with an SSD. I have a PCIe x2 SATA III controller that uses 2 PCIe lanes, and a Samsung 850 Evo 512gb SSD en route and cant wait for that upgrade. This thing is gonna fly!

    1. Glad to hear it helped. I think there are a lot of unannounced mods between revisions that only come to light when you do the kind of thing we’ve done so its always a learning experience.
      Workstations are a blindspot for most PC people so those of us who know can get some real bargains.
      After my first six months using Xeons & ECC I decided I’d never go back. Having a machine that will NEVER crash is such a joy.
      I think you’ll have real fun with your machine; CPUs seem to have plateaued in the last years so age doesn’t matter like it did.
      There obviously are differences in IPC (instructions per clock) between generations but its mainly in I/O where the difference is most obvious.

      PCI-e 2 is perfectly fine. I doubt many GPUs max it out and absolutely MUST have PCI-e 3.
      SATA3, USB3 etc. I sidestepped that by using a PCI-e SSD whos speed is independant of SATA bus limitations.
      Revodrives are great if a bit dated these days. But even tho they’re old my revodrive 3×2 480GB does over 1700 MB/s, over 3x SATA3. And way more than SATA IOP/s as well.

      Best of luck with your modding, I think you’ll enjoy it.
      When its time for an upgrade take a look at the T7500, very similar but takes i7 Xeons and DDR3 ECC. They can be got very cheaply now and the CPUs are also cheap.

      Thanks for leaving a comment, every extra bit of information helps others trying to do the same thing.

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