Install i7-9700k inside HP ProDesk 400 G6 SFF

[jc0023]

I currently have a spare i7-9700k from an old build. I was looking into using it in a home server. I stumbled upon a bare bones ProDesk 400 G6 for a decent price. The datasheet (located here) lists the i7-9700 under processor family, but I don't see a i7-9700k. Before buying the PC, I would like to know if it's compatible.

[NonSequitur777]

@jc0023,

Welcome to our HP Community forum!

You raised an excellent question.

Short story: yes, your i7-9700K (95-watt TDP) is compatible with the HP ProDesk 400 G6 SFF platform.

I can say this with a very high degree of confidence because:

1.) This particular HP ProDesk 400 G6 SFF User successfully installed a higher TDP "K" processor, an i3-8350K (91-watt TDP): https://www.userbenchmark.com/UserRun/48410847.

2.) The 400 G6 MT version is compatible no less with the mighty i9-9900KS (127-watt TDP!): https://www.userbenchmark.com/UserRun/61306481.

3.) The related HP EliteDesk 800 G5 SFF -one of my upgrade projects, was very much compatible with the i7-9700KF, i9-9900KF and the i9-9900KS: https://h30434.www3.hp.com/t5/Desktop-Hardware-and-Upgrade-Questions/Upgrading-HP-EliteDesk-800-G5-S....

Kind Regards,

NonSequitur777

[jc0023 · Accepted solution]

Unfortunately, unless I received a faulty ProDesk motherboard or power supply (unable to test either one), it doesn't seem like it's possible. I keep getting 3 long red beeps and 4 short white beeps. My CPU and ram work in a separate motherboard.

[NonSequitur777]

@jc0023,

Thanks for the update, and sorry to hear about the 3-red / 4-white beep error. That code usually means the integrated graphics failed to initialize.

Since your i7-9700K and RAM work in another board, I’m now thinking this may be an edge-case compatibility issue, possibly due to:

1.) An outdated BIOS: you may need the latest BIOS version (02.16.00 Rev.A) -go to: https://support.hp.com/us-en/drivers/hp-prodesk-400-g6-small-form-factor-pc/27733971.

2.) An iGPU firmware mismatch or stepping conflict,

3.) Or maybe even a marginal PSU that can't deliver stable power to initialize graphics.

If you’re up for a little testing, here are a couple of things you might try:

1.) Boot with a low-power discrete GPU (GT 710, RX 550, etc.) to bypass iGPU initialization.

2.) Try flashing the latest BIOS (if you have a compatible CPU to POST with).

3.) Test with a known-good larger wattage PSU.

I still think the i7-9700K should work based on other successful cases, but HP's OEM BIOS can sometimes be temperamental with higher-TDP or newer CPU steppings.

Kind Regards,

NonSequitur777