power options - additional internal hdd

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[grue]

if i wanted to power additional internal hdd without splitting a feed from the optical bay is there an option elsewhere in a MP 2008?

there are some posts about taking a feed for a high spec video card from the motherboard - I think somewhere near the ODD ports - would that work?

any other alternates?

if any options possible then what cable would you recommend?

i'm uk based which probably limits the cable options a little

I'm slightly confused, are you wanting to power internal HDDs in addition to the four pre-wired SATA bays?

 

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[nanofrog]

yes additional internal hdd on top of the 4 existing.

looking at what options to get power to the drive(s).

i know one way is to take a feed from the optical bay.

interested in what other options exist?

Using the available molex connector from the empty optical bay is the simplest and easiest solution. If you still need another connection at that location, just use a splitter/Y adapter.

If you can get the power connector off the backplane connector, you may be able to use a Y adapter/splitter with the correct molex/SATA connectors. Otherwise, you could hack the power connection itself if you have the skills and inclination to do so.

The PCIe connector on the logic board wouldn't be an option. I've never seen the cabling. What does exist would have male and female connections reversed of what you need.

Why do you not to want to use the 4 pin molex connector available?

 

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[nanofrog]

at the minute both optical bays are in use with dvd drives and will be until i get around to re-ripping my cd's as lossless. with 900+ to do, i want access to as many optical drives as possible - already have access to a 3rd in external case

OK. You have and need both DVD drives.
Not certain on HDD's though.
How many do you have installed internally now?
How many do you plan to add?

am considering placing up to 3 or even 4 hdd's in the space above the cpu & memory sections and so even if using splitters and powering 2 optical + 2 hdd all from the optical bay is ok (am interested in feedback here), that still leaves me with a need to power the last hdd

I can find you power somewhere I should think.
Just not sure of the exact configuration. Answers to this may help immensely.

note that i haven't yet tried the above for space but it looks like it might be possible. i understand that the hdd's will be unmounted and so there will be a number of risks. but the MP has very little chance of being bumped/disturbed where i have it and i'll ensure that there's no chance or shorting out the motherboard.

There may be another way. Perhaps the only one, as I'm not sure how you plan to mount additional drives with all four drive bays occupied as well as both optical bays. The Mac Pro is woefully inadequate in available drive bays.

It seems the answer may lie with an external enclosure. The number of drives would help dictate the size.
Are you looking for them to act individually, or in a RAID configuration?
One way would be to use an eSATA card, and eSATA enclosures. Depending on the card and number of drives, a PM (port multiplier) enclosure may be required.

RAID opens up other possibilities. MultiLane, MiniSAS for example.

Do you mean the connector from the PSU itself to the backplane/motherboard? Re hacking - am unlikely to go much further than using off the shelf cable/components that will do a job. Hacking is something that i might consider doing to the new external cables/connectors themselves, but not something i'd do to the MP i'd like to be in a position to return the MP to stock at any time.

I can certainly understand this.

By PCIe connector do you mean the power connector on the main board near the ODD ports?

Yes.

am interested in why you think there wouldn't be a cable to convert the PCIe connector - is this because the electrical specs are different or because it's not a mod done in the PC world?

Look at the connections backwards. The PCIe cable attaches to the logic board (motherboard). The other end is a female 4 pin Molex connector. So to make this a possibility, you need a male 4 pin Molex to male 4 pin Molex cable. This would then allow you to power an HDD. Now I assume it will require a SATA power connector, you then need a 4 pin Molex to SATA power cable to finally connect to the drive.

The PCIe cable and the Molex to SATA power cables are easy to find. Not so sure on the male to male 4 pin Molex. Didn't see one on span.com.

There is a solution though. The 4 pin male to male cable could be substituted with a power splitter (molex). Just not as elegant as the male to male only.

Does this make sense to you?

BTW, I know span.com can provide the cabling. Not sure where else. Maybe eBay UK?

 

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[nanofrog]

ok so have all 4 hdd sleds used. looking to add another 3 or 4 hdds if possible

This is going to be incredibly difficult in the Mac Pro, and not advised. Not only the physical space issue, but the related thermal problems. The Mac Pro doesn't have the best thermal design I've seen. Not by a long shot.

In my delusions, I was hoping to attach an additional drive directly beneath the drive mounted in each sled.

Another investigation led me to a 4-2.5" internal drive bay. Fits in a single 5.25". It could work, if you are willing to mod the front of the case. There goes the warranty... No purely internal version of this (no case mods required).

One last possibility, and I think doable, is to buy a proper full tower case, and perform a Mac Pro transplant. If you, or I attempt such a thing, it might be a good idea to use a larger power supply, as they tend to have nice long cables. Otherwise, the current supply cabling would likely have to be modded for length. Again, the warranty thing...

The only other solution I know of, and actually works, requires the use of the optical bays. Out of the question in your set-up.

Agreed that's why i'm thinking of the 'shelf' above the cpu/memory

If you do this, your Mac Pro will almost certainly run blazingly hot. It will not only add any heat generated by the drives themselves, but restrict what air movement is currently possible.

This and the physical space available in the Mac Pro aren't up to par for a workstation IMO. I'm in the same boat. 4 drive sleds is a joke for this class of machine.

Looking to avoid external enclosure - issues with space, additional cost etc. appreciate that there are benefits just dont want to go there at this stage.

For all practical intent, there really won't be a choice in this matter I'm afraid. I would have mentioned this sooner, but didn't realize the quantity of drives you need.

There are a few threads on enclosures, but I don't mind trying to help you locate a suitable box that won't break the bank.

What exactly do you need to do with these? RAID or individual drives (JBOD)?

have found the following which look like they might do the job in a cobbled together way?

http://www.dabs.com/ProductView.asp...1125&NavigationKey=11125,4294952704&InMerch=1
http://www.dabs.com/productview.asp...&SearchKey=All&SearchMode=All&NavigationKey=0
http://www.dabs.com/productview.asp...lectedId=11125&NavigationKey=11125,4294952704

The cables you linked won't work. Wrong genders. Other reason as well, so keep reading.

but in doing the digging have a question about the voltages supplied on the PCIe aux power connector on the logic board.

This page says that Sata discs need 12V and 5V as a minimum
http://en.wikipedia.org/wiki/Serial_ATA#Power_Supply

This page says that MP PCIe slots provide 12V and 3.3V
http://developer.apple.com/document...mentation.html#//apple_ref/doc/uid/TP40003937
implying that the PCIe aux power connector on the logic board would also supply 12V and 3.3V and so won't supply the required 5V for hdds?

I was thinking they about the supplied voltages from the PCI-X standard, which has a +3.3, +5.0, and +12.0 V supply.

You are correct, as the PCIe only uses the +3.3 and +12.0 V, and this would be the same on the additional power connector, as it makes no sense to provide a voltage that isn't used.

Sorry about the confusion here.

 

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[nanofrog]

ok then here goes with a revised plan - all feedback +ve/-ve welcome

start with 2 drives in the shelf area - mounted in one of these http://www.noiseblocker.de/en/produkt_entkoppler_nb-xswing.php for spacing and air flow. since i'm using the stock graphics card then i'm generating less heat in this area than some of the more powerful options and hoping to stay within the capability of the MP design.

I've looked at these before. They look good, and may do the job quite well. My issue was that slot 4 needed to be retained for use, as the noiseblockers would almost certainly prevent the use of it. If it isn't an issue, it may well be worth the effort. I should have mentioned them, but had forgotten ATM. Sorry.

Other members have looked to these as a possible solution, but I don't know if anyone has actually tried them in a Mac Pro.

As the MP isnt designed to have drives here then possibly use smcfancontrol to set a higher base speed.

Quite useful program. I can't imagine this not working, albeit a bit noisy.

power from the optical area using these http://www.dabs.com/productview.aspx?Quicklinx=3ZLM & http://www.dabs.com/productview.aspx?Quicklinx=4KX6

So the thing here is - how much power can we actually draw from the optical area. We know that the Maxconnect solution allows 4 HDDs.

It would depend on
1. What the connector is able to provide in terms of current.
2. Number of devices (existing power draw) that is on this particular rail.

That said, I would think it shouldn't be a problem, as the two optical drives would likely be the only devices attached. I'm estimating 12V@20A which is common to a 1kW PSU or so. Thus a total of 8 drives would be possible.

So how does 2 DVD and 2 HDDs compare with 4 HDDs in terms of worst case current draw?

Optical drives are about the same draw as an HDD. Avg use is ~25W, so add 10W for startup. (I usually try to figure power based on startup, not idle/avg draw).

Of course if i look to go further then it could be 2 DVD and 3 or even 4 HDDs all fed from the optical area.

Adding 4 HDD's shouldn't be a problem in the slightest. This is assuming there isn't any other devices attached to this rail.

Also understand that on spin up a HDD can use 3 times as much power as normal. but i'm not clear if the MP 2008 will stagger spin up times and even if it does will it do it with drives not mounted in bays 1-4?

IIRC, it does on the 4 drive bays. The ODD ports, I don't really know.

if 2 HDDs is successful then add a 3rd and possibly a 4th drive later using same cable set up - assuming sufficient power from the optical bay and sufficent 'shelf' space.

Use these:
Molex splitter (x1)
SATA power (x2)

These cables would allow you to run 4 drives.

Found the noiseblockers for $9.99GBP /set
So the whole thing would be $49.09GBP (VAT included), but no S/H. No idea how this would be to you, but would expect any external box to be more.

 

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[nanofrog]

Thanks NF.

Those look like the parts for me - as you say a touch more cost effective and space efficient than a NAS box.

Another quick q, then i should be good to go

If i draw too much current on the optical power cable - what can i expect .... blown fuse or even blown psu? .... maybe unstable disc performance due to a lack of current when required?

No fuses in PSU's that I've seen.

It can take it for a very brief period of time (millisecond range). Decent ones do have some protection built in. But you shouldn't rely on this.

When a PSU is overdrawn, it gets incredibly hot. So hot in fact they can glow cherry red. At some point the voltage regs go out, creating a direct short. Total melt-down, and they have a very nasty habit of taking stuff with it. Mem, motherboards, and CPUs in particular.

In the case of a massive current draw, the circuit breaker in the panel will trip. It's when they draw too much current for the PSU, but not the breaker that the danger zone exists.

Watch the temps like a hawk. Also, if it's drawing too much current, you would likely see some obvious aberrant behavior.

 

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[nanofrog]

good advice - will keep an eye on things

order placed - will update if i can get things operational

Looking forward to seeing how it goes. Particular the X Swing.
Maybe the upcoming Mac Pro will eliminate the slot issue for me.

 

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a little late.........a little long

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