Great systems for the upgrader! Mine arrived clean, with a recent BIOS and the 700w PSU and the lower front performance fan installed. W10p retail version, woot.Thank you ConfigureSystem for a clean refurb that adds value. [And thanks Amazon, for shipping it to Alaska]For those who don't know, you can update to the 4/23 BIOS at HP's support site and drop in most any Xeon E5 16xx, 26xx, or 46xx V3 or V4 CPU from here or eBay.You can also drop in 8x32gb sticks of 2133 with a V3 cpu, or 2400t ECC quad-channel ram if you upgrade to a V4 Xeon.  22c/44t Xeon with 256gigs of ram. 8DThere's also 2x PCIE3 x16, and a 3.0 x8 slot on the PCI bus, and 3x PCIE 2.0 and 6x SATA3 run by the Intel C612 chipset. Motherboard was built by Supermicro for HP.Downsides to this rig are few. The single-fan cpu cooler is good for 145w TDP, but not 24/7 [HP made a vapor cooler, but they're rare and precious on the aftermarket.]You'll want the not-cheap Memory Cooling Solution if you install >4 sticks of ram.  You can jumper the 6-pin connector per youtube to avoid the POST code, but you'll never feel right about it. The cpu cooler dumps heat on the aft sticks. You can feel it and hwinfo will show it.The BIOS, while updated by HP in 4/2023, isn't as nice as the ones in the Z640 and Z840.The 92mm rear case fan will need help if you drop in a 3090, or any modern GPU that doesn't use a squirrel cage fan and exhaust out the rear. Case cooling is definitely the bottleneck.But it's not superhard to remedy. Nor are case swaps...