Could you please tell me what my PSU needs to provide in terms of connectors and power delivery to satisfy the backplane? Is it still 4x Molex?
I have a Corsair RM650x, which has one peripheral cable that splits into four Molex cables. Is that enough, or would it be insufficient/dangerous?
TL:DR The PSU should provide power to the backplane via at least two 4-pin molex connected to separate SATA/PATA ports on the PSU. In your situation you could buy another peripheral cable (Premium Individually Sleeved Peripheral Cable, Type 4 (Generation 3) - Blue), order some custom cables from cablemod, or since you have a Corsair PSU with pinout compatible with the ones 45HL are shipping with the full build I believe if you ask nicely to info@45homelab.com after placing your order they will include a set of the custom length molex cables they use for the full build with your order for a reasonable fee. Custom length cables–whether from 45HL or cablemod–are nice because there then isn’t a lot of extra wire and connector plugs crammed around the PSU.
The longer details:
If we talk just about powering 15 drives on the backplane and ignore all the other requirements of your system (CPU, GPU, HBA, NIC, SSDs, …) …
The main factor in power delivery to the backplane is the amp rating of a single molex connector and the gauge of wire used in the cable. The numbers are a bit fuzzy, can depend on temperature and all other minutia, but in simple round numbers, think of a single PATA cable from the PSU (regardless of the number of molex connctors on it) of being rated up to 10A. Then consider spinning HDDs. A HDD needs about 2.5A for spin-up and will have a sustained load of 1A. Again, very round numbers and that depends on the drive manufacturer, whether it is an Enterprise class drive, SAS/SATA, 12V vs 5V current, etc.
So, a backplane loaded with 15 drives will hit a peak of something like 37A for a few seconds during spin-up and have a sustained load after that of about 15A. The backplane has four molex connectors and it draws the current it needs across all of the connectors that are connected equally. So, if there is only one cable connected for the backplane it will be drawing 15A over a cable only rated for 10A or so. That’s why you should have at least two separate cables from the PSU to the backplane, and the more the better as it just reduces the load on any single cable, so connecting four separate cables would be best. But two is fine; exceeding the amp rating for the momentary spin up spike is ok, and there are ways to do staggered spin up.
Depending on your CPU and so on, 650W is a bit on the low side for a 15-drive system. Their entry point for the v 1.0 was 750W. Of course if you have an older 35W max TDP CPU or something that’s fine. You haven’t given any details of the rest of the system you plan to build or move over.
Thank you for your informative answer! It is very much appreciated!
Currently, my system takes around 80 watts for seven HDDs, two NVMEs, and one SATA SSD. My CPU is a Ryzen 5950X. I did not provide more build details because I am not totally sure yet.
I also want to fit a GPU for AI purposes, but I’m waiting to see if 45Drives will build a device large enough for the rumored 24 GB version of the RTX 5070 Ti Super.
We plan on releasing a 5U version of the HL15, which will be designed to hold any GPU on the market is our goal.
Currently, we have one in our lab with a 4090 in it.
If you only put seven or eight drives in the backplane your one PATA cable would be fine, but I imagine that in looking at an HL15 you are also thinking about adding more drives. If you plan to add AI GPU(s) to the mix, I’d spend the couple hundred extra for the chassis with PSU unless the VAT and import duties are particularly onerous.
There’s a development picture of the XL version here; **Sneak Peek Alert! – HL15 Beast Incoming **. The intent is to support the largest GPUs and EATX motherboards, so it is going to have to be 5U and probably about 5 inches deeper (25 inches total). It isn’t going to be compact and space efficient. Right now, I don’t think they’re looking at a version of the HL15 with its current dimensions, but trading some of the drive bays for longer PCIe cards, eg.
In the HL15 v2 full build you could run dual 16 GB GPUs to get 32 GB VRAM. There are 16GB GPUs around, like some versions of the 4070 Ti Super or AMD Radeon Pro’s that will fit in the HL15’s motherboard chamlber.