HP xw8600 wanting to put 3 disk cage in space of two 5.25 spaces but woried about overheating

[hput3]

There are 4 HDD Cages available but I haven't them for 2 5.25 spaces, I'm looking at several 3 hdd cages that do that,  but, I wonder if that will lead to overheating especially as I plan to work out a way to get another 3 disks in there or at least 1 since I run zfs filesystem and use 2 matched disk pairs for the storage pools.

I already have 4 hdd on board and as some of you will know there is a (hard to exceed) 2 GB limit on this old of HP hardware (2008).  Means you need more disks to get the  space. I'll be needing at least 1 more hdd  just to make my matched pares add up.

I'm pretty sure I will be wanting more down the road, so it probably won't be just the  extra heat from the 5.25 spaces loaded with drives

So ,curious what others here do get more drives into an xw8600.

Also wondering about more fans and where to put them.  Hoping some of the experienced hands here will be able to coach me a little.

[DGroves]

as long as the drives are 5600 rpm or lower heat will not be a issue

there are 4 bay, SATA 2.5 enclosures that fit a 5.25 bay, using two of these allows 8 drives to be used, but such bays are approx 70/80 dollars each + the drive cost

you can buy a complete z400 system (rev 2 board) for around 180.00 (z420 for 230.00) which will work with larger capacity drives

7500 rpm may cause issues and 10k rpm will definitely cause a heat issue

one last time, sinking money into a old system like this is not a very good idea you will be better served with a platform that is based on a newer chipset as the end cost will be about the same