Weirdest thing on graphics card

[Soapy]

I bought a graphics card for a friend of mine (ATI Radeon HD 7750 1GB GDDR5 OC) and on the box it said crossfire compatible. So I thought oh cool this might be fun to test out. Now I have the same card as well since i bought it for myself a year ago. I started looking into the cards and see how its crossfire compatible as it says on the box but it has no crossfire connectors so i cant put the crossfire wire on those two cards. So here's a question is it possible that you can hook up crossfire without the wire like through the mb itself?

[sergle]

Couldn't edit my post, but can't you just do this (I've never had an ATI card)

[Soapy]

Nope it wont identifty 2 of them only 1

[KEN]

Check the box again it will say CrossfireX compatible not Crossfire compatible.
They work in CrossfireX and require PCIE slot that's why you didn't get a bridge ("Crossfire Wire") with them.
What motherboard are you using? are you sure it have 2 PCIE slots?
Also what PSU do you have ? tell me the exact make and model of it.

[Soapy]

I use B75-D3V Gygabite board

[Sethioz]

1. as far as i know, not all ATI cards need the Crossfire bridge, so they should work without.
2. does your windows detect 2 cards? check with whatever you can.
3. Does your motherboard support Crossfire? it's all about money, motherboard companies have to pay lot of money to microsoft to get it SLI / Crossfire certified, if it's not, then windows 7 (probably all new ones and maybe xp too) just refuses to detect Crossfire / SLI for you.
My old mobo didn't support SLI and i had to use "HyperSLI Hack" to enable it, worked perfectly tho, so only problem was microsoft not getting paid enough.

[KEN]

Your mobo supports 2-way CrossFireX.
Are you sure both cards are working?
Did you try them one by one?

Also, tell me about your PSU. It's most important. Tell me exactly which one you have, make and model. Maybe it's not powerfull enough to power 2 cards.

[Sethioz]

Also, tell me about your PSU. It's most important. Tell me exactly which one you have, make and model. Maybe it's not powerfull enough to power 2 cards.

If PSU is not powerful enough, it will burn, that simple. Sometimes you can put more load onto PSU than it gives out, if it has good cooling, it just gets quite hot, but won't burn. I put GTX550Ti into my single core PC that has like 350w PSU and it worked fine (It didn't even have PCI-E power, so i used MOLEX to PCI-E), it was under load for about 3-4 months, PSU was running quite hot, but so far still works.

[Soapy]

Ah it started to work somehow after cleaning the MB sockets from dust. So thanks for the help :)

[KEN]

Some PSU's just wont power it if it's too much. Some even shuts down.

Your problem was simple card not placed well on mobo I guess :P

[Sethioz]

I'm not aware of any power supply (PC or not) that has an actual limiter on it, if you go over limit, you will exhaust the supply and it will overheat and burn.
I haven't burned a PSU, but i did manage to burn few DC adapters, i wasn't sure how much load i put on them, they got real hot and boof.
Even tho you can get a watt meter to see the usage, there's no actual way of limiting the wattage.

If you talking about powering 200w card with 50w, then yes, card won't get enough power to even boot up and therefore it fails to start and won't use any power at all. it might draw the max power for a second, but that's about it and usually that's not enough to burn out PSU.

But this sounds like too dusty pc, dust from fans and really stick to things and prevent perfect contact between slots/cards.

[Soapy]

Dust is so annoying even though you make sure that the pc will be dust free but few days later you can see dust collecting up again. Dust already killed 1 of my rams and Mobos.

[Sethioz]

That's why dust filters are MUST HAVE. I made dust filters out of a bug net, because my media pc doesn't have dust filters and it gets very bad even after 1 month.