The base has a very nice mirror finish as you can see.  You might be wondering...were are the screws?  The copper base and brass top are finished to zero tolerances and press fitted together.  Fortunately this is a simple two layer block, so cleaning should be relatively easy by removing the barbs and accessing the barb entrys.  This does however mean, it would be very difficult to dissassemble the block for a detailed cleaning, but I think in general most users will be fine with flushing the block from the entry points as that's likely where any system debris would stop as well.

But before we finally proceed to testing, how about a macro of those pins...The following is a look down one of the G1/4 barb holes for scale.  Now that's what I call "Micro Machining" very nice!

Delta V1 vs Delta V2

The block revision between delata 1 and 2 is a fairly simple one.  V1 had a relatively simple cirulcar barb entrance and V2 added in a channenl cut into the barbs that spreads the flow over a great area of the pins.  First here are some internal pictures provided to me by XSPC of the V1 opened up.  You can see the relieve cut into the top was cirlces that were just slightly larger than the barb openings.

Delta V2 added another set of cuts that run up and down and distribute the flow over the base.  Here is a drawing that XSPC provided to me that helps explain that.  

Hydraulics and Pressure Drop Testing

The most scientific way to determine a blocks hydraulic resistance is to test pressure drop. Pressure drop is a measurement of pressure loss across a block that varies with flow rate.  This is basically a measurement of energy loss, and directly influences how much flow rate you will have.

Equipment:

• Dwyer Digital Manometer 477 Mark IV - Accuracy .5% of Full Scale.  Range 0-20.00 PSI range, Resolution .01 PSI
• King Instruments 7520 Series 0-5GPM, 250mm scale - Accuracy 2% of Full Scale.  Range 0-5GPM, Resolution .1 GPM (can be interpolated to .02GPM)
• Water Source - Household water pressure - 50PSI at >5GPM - Because flow rate readings are instantaneous, household tap water and water pressure are a good and powerful source for pressure drop testing.

And my results are as follows, the pressure drop was very very low (VERY GOOD!):

And if you're not familiar with what this means, I'm providing a relative chart below with several CPU waterblocks.  It is particularly important to have low pressure drop when installing multiple block loops because every block in that loop creates restriction and too much on any one block can potentially reduce flow rates enough to influence performance on the rest of the system.  So too much restriction can mean less performance on other blocks and the radiator dissipating the heat.

 The XSPC X2O Delta V2 has excellent flow rate characteristics.  It nearly ties the Danger Den MC-TDX for being the least restrictive micropin style CPU block, very impressive!  It appears the very large and tall pins are providing a very large array to distribute flows and reduce resistance.