In my homelab, I run HP servers. I’ve always liked HP servers since my employer switched to them from Dell in 2012. At home, I’ve ran a HP ProLiant DL160 G6 for a couple years now. It’s a beast! Very reliable hardware and doesn’t make too much noise. But there’s one problem with older generations: it’s power hungry. This can add up and I’ll show you comparing similar servers.
When you’re looking to buy a server, it might be tempting to buy an older server that costs much less than a newer generation. Though, if you can afford a newer generation, I encurage you to get the newer generation.
Power Consumption Measuring
I have my internet gear connected to a UPS (this includes my pfSense firewall, network switch, cable modem) and I also have a desktop that I remote into plugged in as well. To measure my usage, I have a Kill-a-Watt that the UPS plugs into.
The Cost of old Hardware
I like to run stuff until it no longer makes sense to run it and with my G6, I think I’ve hit that point. I bought a HP ProLiant DL360p G8 off eBay with two 4 TB drives and 128 GB of RAM. I installed Proxmox on it and migrated my VMs over. I shut down my old server and noticed my Kill-a-Watt was showing less usage. So for fun, I transferred my G8 server over to a different outlet (thanks dual power supplies!) and plugged in my old G6 server. Here’s what I saw.
239 watts for the server (idling too, as my VMs have been migrated), modem, pfSense firewall, network switch, and small desktop. This doesn’t seem bad, right? Well…
When I have my G8 plugged in with my other stuff, I’m only pulling 185 watts. According to iLO, the G8 is pulling a flat 100 watts. That’s with several VMs running! With nothing running, I can probably pull around 95 watts or so.
Calculating the Cost
Time to break out the calculators!
My G8 server under my normal current load only uses 100 watts (this can change, but looking at what’s running, this is what I mostly expect).
kWh = (watts x hours) / 1000
If we plug in some numbers, we get 72 kWh per month. Since it’s “winter”, I look at my current rate table for winter and I’m charged 2.1086 cents per kWh for distribution, 3.5826 cents per kWh for generation. My electric company also charges me a transmission charge of 0.970 cents per kWh.
72 * 2.1086 = 151.8192 cents, or in billing terms, $1.52 for distribution.
72 * 3.5826 = 257.9472 cents, or in billing terms, $2.58 for generation.
72 * 0.970 = 69.84 cents, or $0.70 for transmission.
Total cost before taxes, fees, other surcharges: $4.80 monthly.
Now let’s look at the G6 server. This isn’t going to be entirely accurate as the numbers were pulled when it was idle, no VMs running. Just the host OS.
Running the math, we can guestimate 85 watts is my other stuff leaving us with 154 watts idle for the G6. Doing the math, we get 111 kWh (rounded up from 110.88).
111 * 2.1086 = 234.0546 cents, or $2.34 for distribution.
111 * 3.5826 = 397.6686 cents, or $3.98 for generation.
111 * 0.970 = 107.67 cents, or $1.08 for transmission.
Total cost before taxes, fees, other surcharges: $7.40 monthly.
Difference between G6 and G8: $2.60 savings monthly, or $31.20 annually.
Almost $3 monthly difference. And that’s with the G6 not under a load. I bet if I turned all those VMs back on, it would probably run 200 watts or so, which would make sense because I recall seeing the Kill-a-Watt report ~430 watts or so before I got my G8.
Keep in mind, this also doesn’t factor in other costs like cooling.
Getting the Right Hardware
I will always tell you to get the newest hardware you can without breaking the bank. If you choice is a HP ProLiant DL160 G6 or an HP ProLiant DL360 G8 and you can afford the G8, go with the G8. The power savings will add up. The power supplies are more efficient, the CPUs are more efficient, the RAM is more efficient. The cooling is also more efficient (and quieter). All of this makes a big difference.