Why is my computer slicing me?

September 14, 2006 2:44 PM

What's inside my computer that's causing little slices on my fingertips? The last two times I've opened up one of my computers, I've gotten long, shallow cuts on my fingertips that I didn't notice until I was closing everything up and saw blood on my hand.

It first happened a couple of weeks ago and then again today; the last time there were three parallel cuts, but this time there was only one.

I'm not worried about the cuts themselves -- they are simply an annoyance -- but I am very curious about how I'm getting them.

I've looked inside the box but can't see anything that I can easily relate to the injuries. It's an ASUS Barebones Vintage. Here is a picture of the open box, and a closeup of the area where I was doing most of the work. Here's a picture of my cut finger (ring finger of my left hand).

The first time the injuries happened when I was inserting a firewire card into a PCI slot. Today, here's everything I did:

1. Unscrewed and removed outer covering
2. Blew out dust with a compressed air canister
3. Removed plate covering AGP slot
4. Moved the PCI card to lower slot (because of the size of the new video card)
5. Inserted new video card in AGP slot
6. Rearranged a couple of power supply cables
7. Replaced covering

(As a side note, a couple of days ago I pulled this exact same video card out of another computer and put a new one in, but didn't get any cuts; there seems to be something within this particular box that's causing the problem.)

Any ideas?

posted by camcgee to technology (16 comments total)

Inexpensive computer cases are notorious for having extremely sharp edges. It's just a piece of steel, stamped out of a plate and bent into shape. Grinding the sharp edges off is a low priority. If you feel around carefully inside the edge of the case, you'll find the sharp bit.
posted by jellicle at 2:51 PM on September 14, 2006

What jellicle said: even 'rounded edges' on cheaper cases tend to be sharp edges bent back over. If you're going to be opening up your system a lot, seriously consider investing in a slightly more expensive case.
posted by holgate at 2:55 PM on September 14, 2006

There's a lot of sharp edges all over the place in computer cases. I don't think I've ever done any significant work inside a PC without bleeding.
posted by CrayDrygu at 3:02 PM on September 14, 2006

Dirty hands:mechanic :: bloody fingers:harware nerd. I look at is as a rite of passage. PCI cards are all sharp.
posted by |n$eCur3 at 3:10 PM on September 14, 2006

jellicle and holgate: Thanks -- the sharp edges of the box seemed like a very likely candidate. However, upon close inspection, none of the edges seem sharp enough to make a cut (this is after sliding a fingertip across the outside edge of the box and all the exposed edges of the case cover).
posted by camcgee at 3:21 PM on September 14, 2006

Dirty hands:mechanic :: bloody fingers:harware nerd. I look at is as a rite of passage.

Enh. As I said, I'm not concerned about the cuts themselves. I've cut my hands plenty doing hardware swapping. But I can always either tell when it happens (most commonly) or at least identify afterwards what it was that did the cutting.

The part that is confusing is that I get the cuts without realizing it and then can't tell where I got them afterwards, even after looking at everything and trying to figure out what might cause the cuts.
posted by camcgee at 3:28 PM on September 14, 2006

I go so far as to consider the cuts to be a form of blood sacrifice. If I don't bleed, the computer gods will release the magic smoke.
posted by adipocere at 3:31 PM on September 14, 2006

I have this happen all the time swapping parts out and clean out computers here at work. Sometimes I know right when I cut myself but most of the times, the cuts are similar to a knife cut and I don't even feel the slice. Most of the times they are case edges, but I have had many that I'm not sure where they came from, or how i possibly could have cut that part of my hand.
posted by chrisroberts at 3:32 PM on September 14, 2006

I get the same mystery cuts. I have two cases, and the cheap one is the source of most of the cuts, but not all. I think the remainder is due sharp edges on PCB cards, or else some component of the case (e.g. HD/floppy mount).

If I am paying close attention in an attempt to discover the source of the cuts, I never get any.
posted by clord at 3:35 PM on September 14, 2006

The parallel cuts are more like shallow narrow scrapes, right? That's from IC or socket leads stuck through flow-soldered circuit cards.
posted by Steven C. Den Beste at 4:07 PM on September 14, 2006

Removed plate covering AGP slot

The edges of the metal plates that cover empty card slots are often EXTREMELY sharp. So much so that I've used them as box openers before. Maybe this is where you got cut?
posted by vorfeed at 4:25 PM on September 14, 2006

What adipocere said. Be happy you're getting off so easy--SCSI setups typically required the blood of a goat to get working.
posted by oats at 6:08 PM on September 14, 2006

If your wires are bundled up with zip-ties the cut off ends are often really sharp.

camcgee writes "the sharp edges of the box seemed like a very likely candidate. However, upon close inspection, none of the edges seem sharp enough to make a cut (this is after sliding a fingertip across the outside edge of the box and all the exposed edges of the case cover)"

Check your power supply and optical drive cases

vorfeed writes "The edges of the metal plates that cover empty card slots are often EXTREMELY sharp. So much so that I've used them as box openers before. Maybe this is where you got cut?"

Even worse than the cover plate is the slot openings in the case. Even really good cases often have finger removing sharp edges around the expansion slots.
posted by Mitheral at 8:27 AM on September 15, 2006

Mr den Beste is quite right. If the cuts are parallel and narrowly spaced, they're most likely from solder leads.
posted by jammer at 9:52 AM on September 15, 2006

All the boards are fiberglass, too.
posted by NortonDC at 6:53 PM on September 15, 2006

I always seem to cut myself when swapping cards out and removing the slot covers from cheap cases. Once, it cut me so deep I had to get stitches from the ER. Not fun. Definetly avoid cheap cases.
posted by richter_x at 7:49 PM on September 15, 2006