Adding a new HDD to an old PC
January 13, 2007 12:22 PM   Subscribe

I want to put a new HDD in an old PC and would like to know how. (But please teach me to fish...)

(1) What's the largest HDD I can put in a Dell Optiplex GX1 or a Dell Optiplex GX110? I'm guessing it's 137.4GB. And how can I find the answer to that for any given PC?

(2) If I want to put a large disk in, is it better to buy a new IDE PCI controller card or flash the BIOS? Is it possible to update the BIOS on either of the above machines to accept large modern drives? And, again, how can I find that out for myself?
posted by Busy Old Fool to Computers & Internet (16 answers total)
1. You might bump up against a BIOS limitation. In that case...

2. should get an IDE controller card, which can be had for like $12. Don't plug the system hard disk into it without installing the drivers first, or else Windows won't boot.
posted by neckro23 at 12:46 PM on January 13, 2007

it is sometimes advantageous to buy a card. most add-on hard drive controllers have their own BIOS that handles working the drives, so you don't have to worry about the limit then. they'd also allow you to use SATA hard drives (if you buy a SATA one, natch), which is where everyone is heading anyway.

you may be able to flash the BIOS to remove the size limit - since you have Dells, just head to their support website ( and find the updated BIOS in their downloads section. this is basically the process - you go to the computer or motherboard manufacturer's support site and download the BIOS from there.
posted by mrg at 12:53 PM on January 13, 2007

Another vote for an addon card, even if it's not strictly necessary. They're cheap. They won't have any capacity limits. Disk access will be faster if you don't have two devices sharing one controller as with master/slave. You won't have to fuss with flashing anything, which can be a whole chore in of itself. And most importantly, you can get SATA, which are now cheaper on a $/GB basis (not to mention being on sale/special more and having a greater variety of models) than the old PATA kind, have simpler cabling, and are easier to take with you when you upgrade.
posted by Rhomboid at 1:25 PM on January 13, 2007

nah, no add-on card required (though you may want to consider it.. more below). If your hdd doesn't come with a driver disk, go visit the manufacturer's website. It will install a BIOS overlay, which boots right after your BIOS is done, before the OS takes over. This will allow your OS to recognize the entire size of the drive. (I don't think there is a performance hit).
If your motherboard's IDE spec is ATA 33 or below, your channel speed will be limited to the slowest item. This means that you buy a new HDD (Say ATA 100 or 133) and plug it on the same cable as an ATA 33 drive, that's what your speed will be. With a faster controller (ATA 66 or above), this is no longer an issue.
If you do have an ATA 33 controller, you may want to get yourself an PCI controller card, with Serial ATA. Much smaller wires to route, most SerialATA drives still have old style (molex) connectors on the back (they're white, with 4 plugs inside). SATA power has a black connector. The higher speed of the SATA interconnects will make a difference.
Ok, sorry for the rambly post,
posted by defcom1 at 2:51 PM on January 13, 2007

If memory serves me right, delld use cable select on their boards, so pay attention how the old grive is jumpered.
posted by raildr at 7:37 PM on January 13, 2007

PREVIEW, dummy PREVIEW. (me talking to myself)
posted by raildr at 8:00 PM on January 13, 2007

If you're going to buy a controller card, do go for the SATA one. There's no need to go hog-wild and get a SATA RAID controller; just a cheap vanilla SATA controller will do.

SATA cabling is much simpler than ATA cabling: each SATA cable goes to only one drive, and there are no jumpers to get wrong. The cables are also physically smaller and much easier to route around inside your PC.

As for learning to fish: the information here is solid, if somewhat dated.
posted by flabdablet at 4:11 AM on January 14, 2007

Response by poster: Thanks for all for the answers and advice so far! Please bear with me a little longer.

From comments here, it seemed that a SATA controller card was the best option, but searching the Dell community forum, I found several messages (1,2,3,4) saying that not all cards work well with my models. 'Promise' cards seem to do OK, but there are also warnings that SATA cards in old Optiplexes are an unknown quantity.

Also, one comment about the GX1 said "adding a PCI 32 bit 33mhz SATA card will starve the bus and otherwise be a problem" (more here) - can anyone explain what that means?

I've also seen people recommend this SATA to IDE Converter instead of a controller card, but I'm not quite clear on the difference. Again, can anyone explain?

Finally, when I try to browse controller cards, I'm faced with many choices even from the same manufacturers - what's the difference between all these cards? (leaving aside the ones with RAID, which I don't need.)
posted by Busy Old Fool at 6:25 AM on January 14, 2007

My SATA recommendation was on general principles, and I hadn't considered the age of your PC. If experienced users on the Dell forums are telling you that SATA is a bad idea for your particular machine, I'd listen to them.

PCI bus starvation is where one card hogs all of the available bandwidth on your PC's expansion bus for a lengthy period, preventing other bus users doing anything with it until that card has finished.

In an older machine such as yours, the transfer rate between a SATA controller and the drive would indeed be faster than the transfer rate between the motherboard and the SATA controller over the PCI bus, which makes the PCI bus the bottleneck. It's generally a bad idea to make a shared bus a bottleneck, if you can avoid doing so.

So your safest course will probably be to get an ATA drive, not a SATA one, and plug it onto the same cable that feeds your existing ATA drive, as a slave.

Some Dells use a hard disk cable with no provision for a slave drive, even though the motherboard controller actually does support them. If your existing hard disk cable doesn't have a spare connector in the middle, you'll need to replace it with a standard ATA cable that does.
posted by flabdablet at 1:28 PM on January 14, 2007

the transfer rate between a SATA controller and the drive would indeed be faster than the transfer rate between the motherboard and the SATA controller over the PCI bus, which makes the PCI bus the bottleneck

That's a bunch of horsepucky if you ask me. Sure the theoretical maximum transfer rate of SATA is 150 Mbyte/s (or 300 Mbyte/s for SATA-2), but the fastest 7200 RPM drives in existance cannot stream data any faster than about 90-95 Mbyte/s on a good day, and that's only on the outermost sectors. Most of the time you'll be in the 60 - 80 Mbyte/s range -- and again this applies only to streaming sequential reads, which is not what the vast majority of disk accesses are (they're random I/O.) That old creaky 33 MHz PCI bus still has a 133 Mbyte/s bandwidth so there's no way you're going to saturate it with one drive. *Maybe* with two, but *only* for long streaming sequential reads. And more importantly, you'd still saturate just as equally with ATA-100 (100 Mbyte/s) or ATA-133 (133 Mbyte/s) as you would with SATA. In other words, the interface could be a gazillion billion bytes per second, but hook it up to a 7200 RPM drive and it doesn't really matter as it can't move bytes any faster than the physical head can read or write them. The only exception is for data in the drive's cache but even the largest caches are only 16 MB which is tiny and couldn't saturate anything.
posted by Rhomboid at 1:44 PM on January 14, 2007

And to illustrate my point, take a look at this 250 GB drive roundup. This article is almost a year old but these are still SATA-2 drives. Note that the absolute fastest transfer rate of the bunch was 71.3 MB/s, and remember that this number only applies to sequential transfers on the outermost sectors. The notion that somehow just by hooking this up to a 300 MB/s interface you can magically saturate a 133 MB/s bus is totally ridiculous
posted by Rhomboid at 1:55 PM on January 14, 2007

You certainly wouldn't saturate it completely, but a 16MByte read from cache at 133Mbytes/sec could saturate it for 120ms. That's enough latency to stuff up a softmodem, for example. The inbuilt ATA-33 controller, on the other hand, wouldn't ever use the PCI bus for more than a few microseconds at a time.

I'm not claiming that installing a SATA controller will reduce the old Dell to a creaking groaning collapse, or even that the PCI bus would regularly saturate; I'm just saying that if an experienced Dell forum user claims that SATA controllers are known to cause problems on older Dells because of bus starvation, he may well not be talking completely out his arse.
posted by flabdablet at 1:58 AM on January 15, 2007

Best answer: Okay, here's a compromise then. Buy the SATA drive and a $20 PCI SATA controller. If it turns out that it does foul up other things on the bus (which I still find really darn unlikely) then you get one of those $20 SATA->PATA adaptors and put the drive on the motherboard's creaky old ATA-33 bus. You're only out $20, you get the performance of a modern SATA drive, and should you ever want to upgrade or move it to a newer system you won't have to fuss with PATA/EIDE controllers.

Note when selecting the SATA controller it doesn't really matter if it's RAID or not. A RAID controller just gives you the option to use RAID, you certainly don't have to. And I'm guessing that the market for people looking for addon controllers that aren't interested in RAID is fairly small, so from a manufacturer's standpoint it doesn't make a lot of sense to not include RAID capability -- and most of these $30 "RAID" controllers are not fully hardware accelerated anyway, they just have a Windows kernel driver that does most of the heavy lifting with a BIOS that can limp along on its own only enough to boot the system. I certainly wouldn't call anything under $100 that doesn't have a battery-backed RAM buffer a true RAID card.
posted by Rhomboid at 3:48 AM on January 15, 2007

Oh, and I forgot to mention that if it was possible for a transfer from the drive's cache to somehow lock up the bus for inordinate amounts of time then it would be equally a problem with ATA/133 controllers (the type found integrated on motherboards for the last half-decade or so) as with SATA. Something tells me that the IDE driver writers were smart enough to not hold up the bus for 120ms at a time, and break up those transfers into smaller chunks.
posted by Rhomboid at 3:52 AM on January 15, 2007

Response by poster: This is my first question and I've learned so much. I'm hugely grateful and will be doling out the best answers soon. Thanks.

Sorry to spring the Dell forums links on y'all. I only found them when searching for SATA after reading your answers. I take flabdablet's point about the specific expertise on those forums, but the poster there who brought up the bus starvation issue, while clearly knowledgable, is sometimes a little heavy on the pasted stock responses and weak on explanations. I tend to trust people who can explain clearly why they know something to be true.

Anyway, one more query while I'm trading on your goodwill - am I right to understand that the only disadvantage of a SATA->PATA adaptor compared to a SATA controller card is that the former goes through the existing bus and thus doesn't allow for as many (HD/DVD etc.) drives to be connected?
posted by Busy Old Fool at 8:24 AM on January 15, 2007

Best answer: The SATA->PATA adapter turns your shiny new SATA drive into a slightly lumpy PATA drive that fits into your system anywhere any other PATA drive would go. It will limit the peak data transfer rate from the drive to whatever the PATA cable and controller it's connected to will support, which is generally slower than what you'd get with a SATA controller card. However, as Rhomboid points out above, the drive to motherboard pathway is rarely the bottleneck in hard disk transfers - the usual limiting factors are actual disk read and write rates and especially seek times, so the observable speed disadvantage will probably be quite small.

The main advantages of a SATA->PATA adapter compared to a PCI SATA controller are that you won't need any new drivers to run it, and using it reduces the chances of a saturated PCI bus causing trouble from small to zero.

The main advantages of using a SATA drive plus PATA adapter compared to just using a PATA drive are that most manufacturers' SATA drives have a bigger onboard buffer than is available on their PATA drives, which can speed things up, and that any new PC motherboard you buy today will probably have SATA built in, allowing you to use the same drive in a new PC at full SATA speed with SATA cabling convenience.

On the other hand, the twenty bucks that a SATA controller or adapter will cost you would probably get you an extra fifty GB of drive capacity in the next-size-up PATA drive.

Oh, and if you're going to be running more drives in your PC than you have existing PATA channels to handle: make sure your power supply is grunty enough to cope, and make sure the drives are not jammed up close to each other. Ventilation is a Good Thing.
posted by flabdablet at 9:13 AM on January 15, 2007

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