There's a new one , slightly cheaper, from Germany

https://www.ebay.com/itm/265046713742

but still there are import taxes

Thanks, mazzinia it's around the same price and does not ship to New Zealand

The units were made several years ago for Dell.  Not currently manufactured.  They are unique in that theyh have a small form factor.  Unfortunately, if they've been used for five years they all are at the end of their useful life.  And a lot of people are seeing value in putting higher end Xeons in their workstations. A fixed starting supply of a unique and hard to substitute unit, with units like your failiing under long use, and an increasing demand... Do the math - we're out of luck.

Over the holiday I plan to install dual modern AIO coolers external to my unit.   On top of my computer.  The only thing I'm uncertain about is if the modern PWM connector wiring (with an adapter - I know that Dell's plug is not standard) will suffice.

Yes, I had purchased a new side panel for the T7910.

Brought 2 Dell liquid coolers a year ago on eBay they for second hand so not sure how old they are, maybe they can be reconditioned?

Rang Dell this morning to purchase 2 more new ones, they said they will forward the order to the correct department so waiting to hear back, not holding my breath, just going to get bad news like always with Dell Parts!!

Running 2 x Xeon E5-2697 V4 CPU's and as always CPU2 runs 10-15 degrees C hotter.

Oh, and if you do put in Dell liquid coolers you need to have a panel that has peforations (or you need to get out your Sawz-All). 

It's quite a bit peculiar that one cpu would have this kind of temp difference from the other.

Can you check if by chance you have more cores working in turbo boost , compared to the colder one ?

The CPU temps are about the same difference for me as well right now.

If I can get my act together, over the holidays I'm going to try my dual Artic Liquid Freezer II 280 idea. I'll let you know....   

@mazzinia, the two coolers are in line with each other.  The hot air from one blows direction into the intake of the other.  This is ok if the air temperature only rises 10°F (for a lower TDP processor), but the CPUs that @claytonb and I have are rated around 150W TDP each.   So I get the same temperature difference that @claytonb observes.  It's real.

Again, I think that the coolers were designed for rack systems (I say this because they are so compact) but in a rack setup the CPU air flow would be parallel, not serial.   

@WizardOfBoz2 Ah , I see. But in a real rack system, it's all handled by wind tunnels with the cpu heathsinks being all passive.

I think I never spotted a rack with an active cpu cooler, makes for longer maintenance times in case of failures

The best is to buy two Noctua coolers. I have used those with a dual e5-2699 v4 CPU configuration and 24/7 operation. With 100% loads, the temperature barely reaches 70C.