It is so great when you have a nice HP Server, which is in every HCL of every Software Vendor - from Linux to Windows. But if that is not the case and you want to build a small lab at home or in the garage you might want to decide to build a " Server" on your  knees. And while an installation in a data centers on those fine HP DL 380 or BL blades never have got me any troubles this time I faced many of them! So the setup:

Motherboard: MB ASUS M3N78-VM NF8200 AM2 FSB 5200MHz PCIe mATX
Memory: DDR2 2x2048MB Kit Kingston HyperX 1066MHz CL5
CPU: CPU AMD Phenom X4 9650 2,30GHz AM2+ 4MB 95W
Hard Drive: SATA 320GB WD
CD-ROM: some old IDE CD-ROM

So, with brand name components like this you would think of some HW incompatibility as the last option. Not the case with XenServer 5.5 Installation. Besides the HCL list of XenServer can be found here:

http://hcl.xensource.com/

After burning the CD which I downloaded from Citrix:

http://www.citrix.com/lang/English/lp/lp_1688615.asp

with a good Plextor DVD Writer I put the DVD into the IDE Drive and started my knee build Server. The first error I got couple of times was KERNEL PANIC - the message appeared so fast, that you hardly have a chance to find out what is the problem. But miraculously after it kept rebooting for like 5 times I got to the installation just to receive the message:

Base installation repository was not found at that location. Please check and try again.

The reason - when you have a SATA HDD XenServer assumes you will use SATA DVD - so what you have to do when you see that message is hit ALT + F2 and type:

modprobe ide-generic

that will initialize the IDE CD ROM, then go back to the installation with ALT + F1 . After all the other options were entered and the actual installation started I have got the error

"The decompressor exited with 2 whilst processing package dom0fs"

or similar - sometimes at 6% sometimes at 66% or anything in between. So I burned, while trying to get it to work 4 different CD's (TDK, DVD, CD-RW, DVD-RW) on 2 different Writers. Nothing helped. Thanks to that though I found a really nice tool to put an ISO on your USB stick and make it bootable - all within 10 seconds!

http://unetbootin.sourceforge.net/

That app is really easy to use! When I got the ISO on the USB the error was still there. So it was not the media. Of course, I checked the downloaded ISO with the MD5 tool as well. So being lost here I found that sometimes people would recommend to turn off AHCI for the hard disc and many other options in the BIOS. I even got that far and downloaded the latest BIOS on the Motherboard - it did not helped either. But it give me an idea after all the setting went on default! The reason for all the malfunction and errors was simple. Kingston advertise that the modules I bought were 1066MHz and they indeed are, but on this motherboard, with standard voltage it does not really function on that frequency. And funny enough, when I switched to AUTO the setting for DRAM frequency - my "Server" started in 800MHz mode and the Installation went trough without a single error. At the end I put it back to 1066MHz (so 533MHz in BIOS), but I increased the voltage of the modules by 0,625 and now it works just fine!

UPDATE:

I ended up just putting it back to 800Mhz because it was still rebooting once in a while. So I overclocked the FSB by 10% and now the System is actually faster and more stable. Looks like it is an issues of those RAM modules + this ASUS MB.